Meteorology Notes PDF

1. Definition of Meteorology Meteorology is the scientific study of the atmosphere, focusing on weather processes and forecasting. The term originates from the Greek word "meteoros," which means "high in the air." Meteorologists examine various atmospheric phenomena, weather patterns, and their impa...

1. Definition of Meteorology Meteorology is the scientific study of the atmosphere, focusing on weather processes and forecasting. The term originates from the Greek word "meteoros," which means "high in the air." Meteorologists examine various atmospheric phenomena, weather patterns, and their impacts on the environment and society. 2. The Importance of Meteorology Weather Forecasting: Accurate weather predictions help to prepare for and mitigate the effects of severe weather (e.g., storms, droughts). - Agriculture: Understanding weather patterns is crucial for planting and harvesting crops. - Public Safety: Monitoring weather conditions can prevent disasters and save lives. - Climate Studies: Provides insights into climate change and its implications. 3. Historical Perspectives in Meteorology - Ancient civilizations studied weather to predict seasonal changes crucial for agriculture. - The invention of instruments (e.g., barometers in the 17th century) advanced weather observation. - The establishment of organizations like the National Weather Service (NWS) and the World Meteorological Organization (WMO) has improved global weather monitoring and sharing of meteorological data. 4. Key Terms - Weather: The state of the atmosphere at a specific time and place, including temperature, humidity, precipitation, cloudiness, and wind. - Climate: The average weather conditions over a longer period (typically 30 years) in a given area. - Atmosphere: The layer of gases surrounding the Earth, composed mainly of nitrogen (78%) and oxygen (21%). Composition of the Atmosphere: The Earth’s atmosphere is a mixture of gasses that surrounds the planet. The primary components are: Nitrogen (N₂): Approximately 78% Oxygen (O₂): Approximately 21% Argon (Ar): About 0.93% Carbon Dioxide (CO₂): About 0.04% Trace Gases: Including neon, helium, methane, krypton, and hydrogen. Structure of the Atmosphere: The atmosphere is divided into several layers based on temperature gradients and other properties: Troposphere: Altitude: Extends from the Earth’s surface up to about 8-15 km. Characteristics: Contains most of the atmosphere’s mass, including water vapor and aerosols. Weather phenomena occur in this layer. Temperature: Decreases with altitude. Stratosphere: Altitude: Ranges from about 15 km to 50 km above the Earth’s surface. Characteristics: Contains the ozone layer, which absorbs and scatters ultraviolet solar radiation. Temperature: Increases with altitude due to ozone absorption of UV radiation. Mesosphere: Altitude: Extends from 50 km to about 85 km. Characteristics: Meteors burn up in this layer. Temperature: Decreases with altitude, making it the coldest layer. Thermosphere: Altitude: Ranges from about 85 km to 600 km. Characteristics: Contains ionized gases and is the layer where auroras occur. Temperature: Increases significantly with altitude due to solar activity. Exosphere: Altitude: Extends from about 600 km to 10,000 km. Characteristics: The outermost layer, where atmospheric particles are sparse and can escape into space. Temperature: Varies greatly and is influenced by solar radiation. Temperature: Generally decreases with altitude in the troposphere and mesosphere, but increases in the stratosphere and thermosphere. Pressure: Continuously decreases with altitude across all layers. The ozone layer is a thin layer of a special form of oxygen. Normally, oxygen exists as two oxygen atoms bonded together. But ozone is three oxygen atoms bonded together. It's a toxic gas if we breathe it, but up in the atmosphere it absorbs ultraviolet (UV) rays from the Sun. UV rays would destroy DNA and prevent life from thriving on the surface. When it absorbs UV radiation, the temperature of the surrounding air heats up. This is why the stratosphere heats up. Definitions and Differences: Weather: The short-term state of the atmosphere at a specific place and time, including temperature, humidity, precipitation, wind, and visibility. Weather can change from minute-to-minute, hour-to-hour, day-to-day, and season-to-season. Climate: The long-term average of weather patterns over a significant period, typically 30 years or more. Climate encompasses the statistical data of temperature, humidity, atmospheric pressure, wind, and precipitation in a given region. Key Differences: Time Scale: Weather is short-term (minutes to weeks), while climate is long-term (decades to centuries). Variability: Weather can change rapidly, whereas climate changes more slowly and predictably over time. The Role of Meteorology in Understanding Climate: Data Collection: Meteorologists collect data from satellites, weather stations, and buoys to monitor atmospheric conditions. Weather Forecasting: Short-term predictions help in planning and preparedness for various activities and natural events. Climate Modeling: Long-term data is used to create models that predict future climate patterns and assess the impact of human activities on climate change. Solar Radiation: Definition: Solar radiation is the energy emitted by the sun, primarily in the form of visible light, ultraviolet light, and infrared radiation. Spectrum: Solar radiation includes a range of wavelengths, from short-wavelength ultraviolet (UV) radiation to long-wavelength infrared (IR) radiation. The visible spectrum, which humans can see, lies between UV and IR. Importance: Solar radiation is the primary source of energy for Earth’s climate system. It drives weather patterns, influences climate, and supports life through photosynthesis. Absorption and Reflection:  ○ Reflection: About 30% of incoming solar radiation is reflected back into space by clouds, atmospheric particles, and Earth’s surface (albedo effect). ○ Absorption: The remaining 70% is absorbed by the atmosphere, oceans, and land, warming the planet. Different surfaces absorb solar radiation at different rates, influencing local temperatures. Solar Radiation and Earth’s Energy Budget: ○ Incoming Solar Radiation: The Earth receives about 340 watts per square meter of solar energy on average. This energy is distributed unevenly due to the curvature of the Earth and its axial tilt. ○ Energy Distribution: The equator receives more direct sunlight, leading to higher temperatures, while the poles receive less, resulting in cooler temperatures. ○ Energy Balance: The balance between incoming solar radiation and outgoing infrared radiation determines Earth’s overall temperature. Any imbalance can lead to climate changes. Convection, Conduction, and Radiation: Convection: ○ Definition: The transfer of heat by the movement of fluid (liquid or gas) due to temperature differences. ○ Mechanism: Warm air rises because it is less dense, and cool air sinks, creating a circulation pattern that transfers heat vertically in the atmosphere. ○ Convection Currents form when warm air rises and cool air sinks. This movement creates a cycle that transfers heat vertically. Impact on Weather: Convection currents are responsible for many weather phenomena, including thunderstorms, hurricanes, and trade winds. Global Circulation: The Earth’s rotation and the distribution of land and water create large-scale convection patterns, such as the Hadley, Ferrel, and Polar cells, which influence global climate and weather patterns. ○ Examples: Thunderstorms, sea breezes, and the global atmospheric circulation patterns (Hadley, Ferrel, and Polar cells). ○ Types of Convection: Natural Convection: Driven by buoyancy forces due to temperature differences (e.g., warm air rising from the Earth’s surface such as breezes). Forced Convection: Occurs when an external force, such as wind, moves the fluid (e.g., wind-driven ocean currents). How Ocean Currents Are Formed? Winds: Surface currents in the ocean are primarily driven by wind. The sun heats the Earth’s surface unevenly, creating warm air masses at the equator and cold air masses at the poles. This causes air to rise and sink, creating areas of low and high pressure, respectively. The movement of these air masses generates winds, which in turn drive ocean currents. Coriolis Effect: The Earth’s rotation causes moving air and water to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. This deflection, known as the Coriolis effect, influences the direction of ocean currents. Gyres: The combination of wind-driven currents and the Coriolis effect creates large circular current systems called gyres. Water is deflected towards the center of these gyres, causing it to “pile up” slightly. Gravity then pulls the water back down, fueling the rotation of the gyre. These factors together create the complex system of ocean currents that play a crucial role in regulating the Earth’s climate. Conduction: ○ Definition: The transfer of heat through direct contact between molecules. ○ Mechanism: Heat moves from warmer to cooler areas until thermal equilibrium is reached. This process is more efficient in solids than in gases or liquids. ○ Examples: Heat transfer from the Earth’s surface to the air in contact with it, warming of the ground during the day, and cooling at night. ○ Conduction in the Atmosphere: Surface Heating: During the day, the Earth’s surface absorbs solar radiation and heats up. This heat is then transferred to the air in contact with the surface through conduction. Nighttime Cooling: At night, the surface loses heat through radiation, and the air in contact with the surface cools down through conduction. Role in Weather: Conduction is important in the formation of temperature inversions, where a layer of cool air is trapped near the surface by a layer of warmer air above. Radiation: ○ Definition: The transfer of energy through electromagnetic waves without the need for a medium. ○ Mechanism: Energy is emitted by all objects in the form of infrared radiation. The Earth absorbs solar radiation and re-emits it as infrared radiation. ○ Greenhouse Effect: Certain gases in the atmosphere (e.g., carbon dioxide, methane, water vapor) trap some of the outgoing infrared radiation, warming the atmosphere and surface. ○ Examples: The warmth felt from the sun, the cooling effect of radiative heat loss at night, and the role of greenhouse gases in regulating Earth’s temperature. ○ Radiative Transfer: Emission and Absorption: All objects emit radiation based on their temperature. The Earth emits infrared radiation, which is absorbed and re-emitted by greenhouse gases in the atmosphere. Greenhouse Effect: The greenhouse effect is a natural process that warms the Earth’s surface. Without it, the average temperature of the Earth would be much colder. Human Impact: Human activities, such as burning fossil fuels and deforestation, increase the concentration of greenhouse gases, enhancing the greenhouse effect and leading to global warming. Introduction Weather systems are driven by the movement and interaction of air masses, which are influenced by pressure differences in the atmosphere. Understanding these systems is crucial for predicting weather patterns and preparing for various weather conditions. Low-Pressure Systems Low-pressure systems are areas where the atmospheric pressure is lower than the surrounding areas. These systems are often associated with cloudy skies, precipitation, and strong winds. They form when warm air rises, creating a vacuum that pulls in cooler air from the surroundings. Low-pressure systems can lead to storms, rain, and other forms of precipitation. High-Pressure Systems High-pressure systems are areas where the atmospheric pressure is higher than the surrounding areas. These systems are typically associated with clear skies and calm weather. They form when cool air descends, increasing the pressure on the surface.  High-pressure systems usually bring fair weather and are often referred to as anticyclones. Cyclones Cyclones are large-scale air masses that rotate around a strong center of low atmospheric pressure. There are tropical cyclones (hurricanes, typhoons) and extratropical cyclones. Cyclones are characterized by strong winds, heavy rain, and can lead to severe weather conditions like thunderstorms and tornadoes. They form over warm ocean waters and are fueled by the heat and moisture from the ocean. Anticyclones Anticyclones are large-scale air masses that rotate around a strong center of high atmospheric pressure. Anticyclones are associated with calm, clear weather and are the opposite of cyclones. They form when air descends from the upper atmosphere, creating high pressure at the surface. Real-World Examples Cyclones: Typhoon Haiyan (2013) in the Philippines, Hurricane Katrina (2005) in the USA. Anticyclones: The Siberian High, which brings cold, dry weather to parts of Asia during winter. Discussion Questions: 1. How do low-pressure systems affect local weather conditions? 2. What are the main differences between cyclones and anticyclones? 3. Can you think of any recent cyclones or anticyclones that have impacted your region? Typhoons vs. Cyclones Definition and Terminology Typhoon: A typhoon is a type of tropical cyclone that forms in the Northwest Pacific Ocean. This region includes the Philippines, Japan, and China. Cyclone: The term “cyclone” is a generic term used for any rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation. Cyclones are called different names depending on where they form: ○ Hurricanes: In the North Atlantic, central North Pacific, and eastern North Pacific. ○ Typhoons: In the Northwest Pacific. ○ Cyclones: In the South Pacific and Indian Ocean Characteristics Both typhoons and cyclones form over warm ocean waters with surface temperatures of at least 26.5°C (80°F). They are fueled by the heat and moisture from the ocean. They have a low-pressure center known as the “eye,” surrounded by a circular “eye wall” that contains the storm’s strongest winds and rain. The intensity of these storms is measured using the Saffir-Simpson scale, which categorizes them based on wind speeds. Regional Differences Typhoons: These storms are common in the Northwest Pacific, affecting countries like the Philippines, Japan, and China. The Philippines, in particular, experiences numerous typhoons each year due to its location in the Pacific typhoon belt. Cyclones: In the Indian Ocean and South Pacific, these storms are simply called cyclones. They can impact countries like India, Australia, and Madagascar. Impact on the Philippines The Philippines is particularly vulnerable to typhoons due to its geographical location. Typhoons can bring heavy rainfall, strong winds, and storm surges, leading to flooding, landslides, and significant damage to infrastructure and agriculture. Some notable typhoons that have impacted the Philippines include: Typhoon Haiyan (Yolanda): One of the strongest tropical cyclones ever recorded, it caused widespread devastation in 2013. Typhoon Goni (Rolly): In 2020, it brought severe damage to the Bicol region and other parts of Luzon. 1. Types of Air Masses Air masses are large bodies of air that have uniform temperature and humidity characteristics. They form over specific regions and acquire the properties of those regions. There are several types of air masses: Tropical Air Masses (T) Maritime Tropical (mT): Warm and moist, forming over tropical oceans, and unstable. The air mass over the Philippine Sea, which brings warm and humid conditions to the Philippines, especially during the southwest monsoon (Habagat) season. Continental Tropical (cT): Hot and dry, forming over deserts and landmasses in tropical regions. While the Philippines does not have deserts, continental tropical air masses can influence the region when they move from nearby landmasses like Australia. Polar Air Masses (P) Maritime Polar (mP): Cool and moist, forming over cold ocean waters. The air mass over the North Pacific Ocean, which can bring cooler and wetter conditions to the northern parts of the Philippines during the northeast monsoon (Amihan) season. Continental Polar (cP): Cold and dry, forming over high-latitude land areas. Continental polar air masses from Siberia can occasionally reach the Philippines, bringing cooler temperatures during the Amihan season. Arctic Air Masses (A) - Extremely cold and dry, forming over the Arctic regions. Although rare, arctic air masses can influence the Philippines indirectly by pushing polar air masses further south, leading to cooler conditions. Equatorial Air Masses (E) - Warm and very moist, forming near the equator. The air mass over the equatorial Pacific Ocean, which contributes to the warm and humid climate of the southern Philippines, particularly in regions like Mindanao. During the southwest monsoon (Habagat) season, the Philippines experiences the influence of maritime tropical (mT) air masses from the Philippine Sea. This results in warm and humid conditions, with frequent heavy rainfall and thunderstorms, especially in the western parts of the country. Conversely, during the northeast monsoon (Amihan) season, maritime polar (mP) air masses from the North Pacific Ocean bring cooler and drier air to the northern and eastern parts of the Philippines, leading to cooler temperatures and less humidity. Weather Fronts A front is a boundary between two different air masses. The interaction between these air masses can lead to various weather phenomena. There are four main types of fronts: Warm Front is characterized by a warm (less dense) air mass moving into a cold air mass. Characterized by gentle uplift. Occur when a warm air mass moves over a cold air mass. Characterized by gradual temperature increase and steady precipitation. Often bring extended periods of rain or snow. Cold Front is characterized by a cold (more dense) air mass is moving into a warmer (less dense) air mass. Characterized by abrupt uplift along the frontal boundary. Occur when a cold air mass moves under a warm air mass, forcing the warm air to rise. Characterized by a sudden drop in temperature and possible thunderstorms. Often bring heavy rain or snow, followed by clear skies. Stationary Front is characterized by a nearly stationary boundary between tow air masses. Frontal boundary is often the focus for gentle to moderate precipitation (if you're under a stationary boundary, it's pretty depressing weather). Occur when two air masses meet but neither is strong enough to move the other. Characterized by prolonged periods of cloudy weather and precipitation. Can lead to flooding if the front remains stationary for an extended period. Occluded Front is an active cold front which overtakes a warmer front and is often associated with a variety of precipitation intensities and duration. There are two types - depending on what type of air mass overtook. If cold air overtook cool air and forced warm air up, then it is a cold-type of occluded front.  If cool air overtook cold air and forced warm air to rise, then it is a warm-type of occluded front. Occluded fronts usually signal the end to the low pressure system (cyclone) driving it. Thunderstorms are storms characterized by lightning and thunder, often accompanied by gusty winds, heavy rain, and hail. They form when warm, humid air rises in an unstable environment, typically due to mechanisms like unequal heating of Earth's surface or the lifting of warm air along fronts or mountains. There are two main categories of thunderstorms: 1. Air-Mass Thunderstorms: These form from scattered cumulonimbus clouds within maritime tropical air masses, often during summer. They are usually short-lived and less severe. 2. Severe Thunderstorms: These benefit from uneven surface heating and lifting mechanisms, often aided by diverging winds aloft. They can produce high winds, damaging hail, flash floods, and tornadoes. Thunderstorms are most common in the tropics, where warm, moist, and unstable air is prevalent. Annually, the Earth experiences about 16 million thunderstorms. In the Philippines, thunderstorms are frequent due to the country's tropical climate. The peak thunderstorm activity occurs during the rainy season, from June to November, particularly in coastal areas and regions with significant topographical features. Thunderstorms are less frequent during the dry season and in areas with less topographical variation. The Philippines, with its warm, moist, and unstable air, provides ideal conditions for the formation of thunderstorms, making them a common occurrence. The Philippines experiences around 20 typhoons and tropical storms annually, with about a quarter of them being particularly destructive. The strongest typhoon to hit the Philippines in recent years was Super Typhoon Rai (Odette) in 2021, which had maximum sustained winds of 195 mph (314 km/h) and caused widespread devastation. The deadliest typhoon was Super Typhoon Haiyan (Yolanda) in 2013, which resulted in over 6,300 deaths and caused catastrophic damage across the central Philippines Air-Mass Thunderstorms Formation and Frequency: In the Philippines, air-mass thunderstorms frequently occur due to the country's tropical maritime (mT) climate. These warm, humid air masses become unstable when heated from below by the warm land surface or lifted along weather fronts or mountain slopes. Air-mass thunderstorms in the Philippines are most common during the rainy season (June to November) when the southwest monsoon (Habagat) brings moist air from the surrounding oceans. They often occur in the afternoon and early evening when surface temperatures are at their highest, forming scattered, isolated cells rather than organized bands. Stages of Development: 1. Cumulus Stage: - Uneven surface heating creates rising air currents, producing cumulonimbus clouds. - Initial fair-weather cumulus clouds may evaporate quickly, but with enough moisture, they grow vertically. - Updrafts dominate, and latent heat release allows clouds to rise higher. - Precipitation begins as the cloud passes the freezing level, leading to downdrafts initiated by drag from falling precipitation and cooling from entrainment (influx of cool, dry air). 2. Mature Stage: - Downdrafts leave the cloud base, releasing precipitation. - At the surface, cool downdrafts spread laterally, felt as sharp, cool gusts. - Updrafts and downdrafts coexist, enlarging the cloud and forming an anvil top at the unstable region's peak. - The most active period, with gusty winds, lightning, heavy rain, and possibly small hail. 3. Dissipating Stage: - Downdrafts dominate, causing entrainment and cooling, leading to the evaporation of the cloud. - Without moisture from updrafts, the cloud dissipates. - Only about 20% of condensed moisture leaves as precipitation, while 80% evaporates back into the atmosphere. Observations and Research: - Important experiments in the late 1940s in Florida and Ohio led to the "Thunderstorm Project," which investigated air-mass thunderstorms using radar, aircraft, and other instruments. The study produced a three-stage life cycle model for air-mass thunderstorms, which remains unchanged after over 70 years. Occurrence: Occurrence refers to the frequency and locations where air-mass thunderstorms are likely to happen. Mountainous Regions: Areas like the Cordillera Central and Sierra Madre experience more air-mass thunderstorms due to intense heating of the air near the mountain slopes, creating upslope movements that generate thunderstorm cells. Sea-to-Land Airflow: Many thunderstorms are triggered by the convergence of sea-to-land airflow, particularly during the southwest monsoon (Habagat). Intertropical Convergence Zone (ITCZ): Near the equator, thunderstorms frequently form along the ITCZ, where converging trade winds create storm activity. Severe Thunderstorms and Supercells Severe Thunderstorms: Definition: Capable of producing heavy downpours, flash flooding, strong winds, large hail, frequent lightning, and possibly tornadoes. Classified as severe if winds exceed 93 km/h (58 mph), hailstones are larger than 1.9 cm (0.75 inches), or they generate a tornado. Frequency:The Philippines experiences a high frequency of severe thunderstorms, primarily due to its location in the Northwestern Pacific Basin, which is the most active tropical cyclone basin in the world. On average, the country encounters around 20 tropical cyclones per year, with about 8 to 9 of them making landfall. The peak season for these cyclones is from July to October, when nearly 70% of the year's typhoons develop Formation: Unlike air-mass thunderstorms, severe thunderstorms can last for hours, aided by strong vertical wind shear that tilts the updrafts, allowing them to persist and maintain strength. Gust Fronts: Outflow boundaries from downdrafts act as mini cold fronts, lifting warm air and creating new thunderstorms. Supercell Thunderstorms: Characteristics: These are powerful, single-cell thunderstorms extending up to 20 km (65,000 feet) in height and lasting several hours, often causing the most dangerous weather conditions. Frequency: Approximately 2,000 to 3,000 supercells occur annually in the U.S., causing a disproportionate amount of severe weather-related damage. While supercells are more common in regions like the central United States, the Philippines can still experience them, especially during the typhoon season when conditions are favorable. These storms can bring intense rainfall, strong winds, and occasionally tornadoes, posing significant risks to life and property Formation: Require strong vertical wind shear, leading to rotating updrafts (mesocyclones) where tornadoes can form. An inversion layer above the surface helps by trapping warm, moist air, allowing it to heat and rise explosively. Complex Structure:Despite being single cells, supercells are complex, often involving rotating updrafts. Squall Lines and Mesoscale Convective Complexes (MCCs): Squall Lines: Narrow bands of thunderstorms, potentially severe, forming ahead of cold fronts due to warm, moist air and upper-level jet stream divergence. Can last for over 10 hours. Drylines: Boundaries with abrupt moisture changes, where denser dry air lifts moist air, triggering thunderstorms. MCCs: Large clusters of thunderstorms forming slow-moving complexes, providing significant rainfall, especially beneficial for agriculture, though sometimes causing severe weather. Lightning and Thunder Lightning is a powerful and sudden electrostatic discharge that occurs during a thunderstorm. It happens when there is a buildup of electrical charge within a cloud or between a cloud and the ground. Fatalities and Injuries: In the Philippines, lightning also poses a significant risk, particularly during the rainy season when thunderstorms are frequent. However, comprehensive statistics on lightning-related fatalities and injuries are not as widely reported or available as they are in the United States. Lightning is a leading cause of storm-related deaths, second only to floods in the United States. Annually, it kills about 100 people and injures over 1,000. Frequency Strikes the ground tens of millions of times each year, making it difficult to issue specific warnings for every flash. Classification: A storm is classified as a thunderstorm if thunder is heard, indicating the presence of lightning. Formation: Charge Separation: Occurs during the formation of cumulonimbus clouds, with different parts of the cloud acquiring positive or negative charges. The goal of lightning is to balance these electrical differences. Types of Lightning: Intracloud Lightning: Occurs within or between clouds, making up about 80% of lightning. Cloud-to-Ground Lightning: Comprises about 20% of lightning, and is the most dangerous and damaging type. Charge Movement: Negative charges in the cloud base repel negative charges on the ground, creating a positive charge on the surface below the cloud. Lightning Strokes: Multiple Strokes: A single flash consists of several strokes, with each stroke separated by roughly 50 milliseconds. Leaders and Return Strokes: Lightning begins with a step leader that ionizes the air, creating a conductive path. The return stroke follows, illuminating the path and discharging the cloud’s charge to the ground. Thunder: Sound Production: Lightning heats the surrounding air to extreme temperatures (up to 33,000°C), causing explosive expansion and the sound waves we hear as thunder. Estimating Distance: The delay between seeing lightning and hearing thunder helps estimate the distance of the lightning strike (sound travels approximately 330 meters per second). Heat Lightning: Distant Lightning: Lightning that occurs more than 20 kilometers away, where thunder is not heard, is popularly called heat lightning. It is the same as regular lightning but is observed from a greater distance. Tornadoes Characteristics: Tornadoes are highly destructive local storms with violent winds and short durations. They form rotating columns of air (vortex) that extend from cumulonimbus clouds to the ground. Wind speeds can exceed 480 km/h (300 mph), causing massive damage and loss of life. Notable Events: In April 2011, a record 753 tornadoes were confirmed in one month in the United States, causing significant fatalities and property damage. The tornado that hit Tuscaloosa, Alabama, and the one in Joplin, Missouri, in May 2011 were particularly deadly and destructive. Formation: Tornadoes are usually associated with severe thunderstorms and can form in any situation that produces severe weather, including cold fronts, squall lines, and tropical cyclones. The most intense tornadoes typically form in association with supercells, which involve rotating updrafts known as mesocyclones. Mesocyclones form due to vertical wind shear, leading to a horizontal rolling motion that can be tilted vertically by updrafts. Development: Tornadoes begin with a mesocyclone, which may precede tornado formation by about 30 minutes. As the mesocyclone stretches and narrows, wind speeds increase, and a funnel cloud may form. If the funnel cloud reaches the ground, it becomes a tornado. Climatology: Tornadoes most often occur along cold fronts or squall lines of midlatitude cyclones, especially in the central United States where contrasting air masses meet. The central U.S. experiences the highest number of tornadoes due to the lack of natural barriers separating polar air from tropical air. Tornado Intensity: Most tornado damage is caused by tremendously strong winds. One commonly used guide to tornado intensity is the Enhanced Fujita Intensity Scale (EF-scale). A rating on the EF-scale is determined by assessing damages produced by a storm. Tornadoes in the Philippines Occurrence: Tornadoes in the Philippines are relatively rare but can occur from March to December, with a higher frequency during the rainy season (June to November). The flat terrain of Central Luzon, particularly in provinces like Pampanga and Tarlac, makes this region the most tornado-affected area in the country. Recent Events: On June 22, 2023, a tornado struck Bacolor town in Pampanga, causing significant damage to 21 houses, a church, and several electric posts. Fortunately, there were no fatalities, but three people sustained minor injuries4. In August 2016, two tornadoes hit parts of Metro Manila during a severe thunderstorm, lasting no longer than five minutes. Safety Measures: During a tornado, it is crucial to seek shelter indoors, away from windows, and stay informed through weather updates. Local governments and disaster response teams are often involved in providing aid and support to affected communities. Tornadoes, while less frequent in the Philippines compared to the United States, still pose a significant threat during severe weather conditions. Staying prepared and informed can help mitigate their impact. Tornado Forecasting Challenges: Tornadoes are small and short-lived, making them difficult to predict and monitor precisely. Timely issuance and dissemination of watches and warnings are critical for protecting life and property. Storm Prediction Center (SPC): Located in Norman, Oklahoma, part of the National Weather Service (NWS) and National Centers for Environmental Prediction (NCEP). Provides accurate forecasts and watches for severe thunderstorms and tornadoes. Outlooks and Watches: Severe Thunderstorm Outlooks: Issued several times daily, identifying areas likely to be affected within the next 6 to 30 hours (Day 1) and extending into the following day (Day 2). Tornado Watches: Alert the public to the possibility of tornadoes over a specified area and time. Typically cover about 65,000 square kilometers (25,000 square miles) for 4 to 6 hours. Tornado Warnings: Issued when a tornado has been sighted or indicated by radar, warning of imminent danger. Cover much smaller areas and are typically in effect for 30 to 60 minutes. Doppler Radar: Improved tracking of thunderstorms and issuance of tornado warnings. Detects motion using the Doppler effect, identifying characteristic circulation patterns of tornadoes. Can detect mesocyclones and tornado circulations, providing lead times up to 13 minutes before tornado formation. Technological Advances: Significant decline in tornado deaths over the past 50 years due to better forecasts and technology. The probability of a location being struck by a tornado is small, but exceptions occur, emphasizing the importance of taking watches and warnings seriously. Operational Challenges: Weak tornadoes can result in numerous warnings, potentially desensitizing the public to more dangerous storms. Not all storms have clear radar signatures, and detection can be subjective. Hurricanes Definition and Characteristics: Hurricanes are intense low-pressure centers forming over tropical or subtropical oceans, characterized by strong cyclonic circulation and intense convective (thunderstorm) activity. Sustained winds must be at least 119 kilometers (74 miles) per hour. Global Terminology: Known as typhoons in the northwestern Pacific and cyclones in the southwestern Pacific and Indian Ocean. Formation and Frequency: Typically form between latitudes 5° and 20° over tropical oceans, except rarely in the South Atlantic and eastern South Pacific.  The western North Pacific experiences the most hurricanes, averaging 20 per year. The North Atlantic sees about five hurricanes annually. Structure: Average mature hurricane size: 600 kilometers (375 miles) across, with pressure dropping significantly from the outer edge to the center. Eye Wall:The area surrounding the storm's center with the highest wind speeds and heaviest rainfall. Eye: The calm center of the storm, characterized by descending air and relatively calm conditions, though not necessarily cloudless. Mechanics: Hurricanes derive energy from the latent heat released during the formation of cumulonimbus clouds. The pressure gradient generates rapid inward spiraling winds that accelerate towards the storm's center due to the conservation of angular momentum. Air rises in the eye wall and is carried outward at the top, allowing more inward flow at the surface. Hurricane Formation and Decay Formation: Hurricanes are fueled by the latent heat released when water vapor condenses. They require large quantities of warm, moist air and form most often in late summer and early fall when sea-surface temperatures reach 27°C (80°F) or higher. Formation is rare in the South Atlantic and eastern South Pacific due to cooler waters and near the equator due to weak Coriolis force. Hurricanes often start as tropical disturbances with weak pressure gradients and little rotation, sometimes triggered by convergence in the ITCZ or easterly waves. As disturbances grow, they develop strong cyclonic rotation, lowering surface pressure and increasing wind speeds. A tropical disturbance can develop into a tropical depression, then a tropical storm, and eventually a hurricane if conditions are favorable. Triggers: Trade wind inversions and strong upper-level winds can inhibit hurricane formation. Favorable conditions include the release of latent heat, creating low-pressure regions and encouraging cyclonic circulation. Hurricane Decay: Hurricanes lose intensity when they move over cooler ocean waters, onto land, or encounter unfavorable atmospheric conditions. Moving onto land cuts off the supply of warm, moist air, rapidly diminishing the hurricane's strength. Increased surface roughness over land slows winds, reducing pressure differences and further weakening the hurricane. Hurricane Destruction Overview: The majority of hurricane-related deaths and damages come from infrequent but powerful storms. The deadliest hurricane in U.S. history was the 1900 Galveston hurricane, while Hurricane Katrina in 2005 was the costliest, with economic impacts exceeding $100 billion. Saffir-Simpson Scale: Used to rank hurricane intensity from Category 1 (least severe) to Category 5 (most severe). Only three Category 5 hurricanes have hit the continental U.S.: Andrew (1992), Camille (1969), and the 1935 Labor Day hurricane. Types of Damage: 1. Storm Surge: ○ The most devastating aspect, responsible for 90% of hurricane-related deaths. ○ A dome of water pushed ashore by hurricane winds, it can cause extreme flooding and destruction, especially in low-lying areas. 2. Wind Damage: ○ Hurricanes generate dangerous winds that can turn debris into deadly projectiles and cause structural damage. ○ High-rise buildings and mobile homes are particularly vulnerable. ○ Hurricanes can also spawn tornadoes, increasing the potential for destruction. 3. Heavy Rains and Inland Flooding: ○ Torrential rains from hurricanes can cause significant flooding, even far inland. ○ Examples include Hurricane Agnes (1972), which caused extensive flooding in Pennsylvania, and Hurricane Camille (1969), which resulted in deadly floods in Virginia. The Philippines frequently experiences powerful typhoons, which are equivalent to hurricanes. Here are some recent examples: 1. Typhoon Kong-Rey (Leon): This typhoon recently skirted the northern Philippines, bringing strong winds and torrential rain. It caused widespread flooding and landslides, resulting in over 100 deaths2. 2. Tropical Storm Trami (Kristine): This storm caused significant devastation in late October 2024, with at least 126 deaths and 500,000 people displaced due to flooding and landslides. The storm dumped an enormous amount of rainfall in a short period, leading to severe flooding2. 3. Typhoon Noru: In September 2022, Typhoon Noru rapidly intensified and prompted evacuations in the northeastern Philippines. It brought sustained winds of 121 mph and gusts up to 149 mph, causing significant damage and forcing thousands to evacuate3. 4. Typhoon Rai: In December 2021, Typhoon Rai hit the southeastern Philippines with winds of up to 195 mph, causing widespread destruction and displacing nearly 100,000 people. Detecting, Tracking, and Monitoring Hurricanes Hurricane Paths: Hurricanes are steered by environmental flow throughout the troposphere, moving like leaves carried by currents. Typically, hurricanes move westward with a slight poleward component due to the Bermuda High's influence. They may curve back out to sea or make landfall, making predictions challenging. Detection and Monitoring Tools: 1. Satellites: ○ Satellites provide critical data for detecting and monitoring tropical storms, even before cyclonic flow develops. ○ They improve storm detection but have limitations in estimating wind speeds and storm positions precisely. 2. Aircraft Reconnaissance: ○ Specially equipped aircraft fly into hurricanes to measure details of their position and development. ○ Data collected are essential for forecasting but are limited to "snapshots" when the storm is near shore. 3. Radar: ○ Land-based Doppler radar monitors hurricanes as they approach the coast, providing detailed information on wind fields, rainfall, and storm movement. ○ Radar is limited to a range of about 320 kilometers (200 miles) from the coast. 4. Data Buoys:  ○ Floating instrument packages in fixed locations provide continuous surface condition measurements over ocean areas. ○ Data from buoys are crucial for daily weather analysis and hurricane warnings. New Tracking Techniques: VORTRAC: ○ Developed to capture sudden intensity changes in hurricanes nearing land. ○ Uses Doppler radar network data to map storm rotational winds and infer central pressure, updating every six minutes. Watches and Warnings: Hurricane Watch: ○ Issued 48 hours in advance of expected tropical storm-force winds, indicating possible hurricane conditions in a specified area. Hurricane Warning: ○ Issued 36 hours in advance, indicating expected hurricane conditions, including dangerously high water and waves. Forecasting Challenges: Adequate lead time is essential to protect life and property. Balancing the need to protect the public while minimizing overwarning is crucial. Introduction Precipitation is a crucial component of the Earth’s water cycle, playing a vital role in replenishing freshwater resources and sustaining ecosystems. It occurs when atmospheric water vapor condenses into water droplets or ice crystals that become heavy enough to fall to the ground due to gravity. Understanding the different types of precipitation and their formation processes is essential for comprehending weather patterns and predicting climatic changes. In this lesson, we will explore the various forms of precipitation, including rain, snow, sleet, and hail. We will delve into the atmospheric conditions and processes that lead to their formation, providing a comprehensive overview of how these phenomena occur. By the end of this lesson, you will be able to identify and describe each type of precipitation, explain their formation mechanisms, and apply this knowledge to real-world weather scenarios. Types of precipitation Type Description Formation Picture Rain Rain consists of liquid water Rain forms through the collision-coalescence process in droplets that fall from clouds warm clouds. Tiny water droplets collide and merge to form when the air temperature is larger droplets. When these droplets become heavy above freezing (0°C or 32°F). enough, they fall to the ground as rain. Snow Snow is composed of ice Snow forms through the ice crystal (Bergeron) process in crystals that form when the air cold clouds. Water vapor condenses directly onto ice temperature is below freezing. crystals, causing them to grow. These crystals stick together to form snowflakes, which fall when they are heavy enough. Sleet Sleet consists of small ice Sleet forms when snowflakes partially melt as they fall pellets that form when raindrops through a layer of warm air and then refreeze into ice pellets freeze before reaching the when they pass through a colder layer near the ground. ground. Hail Hail is made up of balls or lumps Hail forms in thunderstorms with strong updrafts that carry of ice that form in strong raindrops upward into extremely cold areas of the thunderstorms with intense atmosphere. The raindrops freeze and accumulate layers of updrafts ice as they are repeatedly lifted and dropped by the updrafts. When the hailstones become too heavy, they fall to the ground The formation of precipitation involves several key processes: Saturation: Air must become saturated with water vapor, which means it has reached its maximum capacity to hold water vapor at a given temperature. Lifting Mechanisms: Air is lifted to higher altitudes where it cools down, leading to condensation This can happen through orographic lifting (air forced over mountains), frontal lifting (warm air rising over cooler air), or convective lifting (warm air rising from the surface). Three Lifting Mechanisms OROGRAPHIC LIFTING  It results when warm moist air of the ocean is forced to rise by large mountains. As the air rises it cools, moisture in the air condenses and clouds and precipitation result on the windward side of the mountain while the leeward side receives very little. This is common in British Columbia. FRONTAL LIFTING Frontal precipitation results when the leading edge (front) of a warm air mass meets a cool air mass. The warmer air mass is forced up over the cool air. As it rises the warm air cools, moisture in the air condenses, clouds and precipitation result. CONVECTIVE LIFTING Convectional precipitation results from the heating of the earth's surface that causes air to rise rapidly. As the air rises, it cools and moisture condenses into clouds and precipitation. Condensation: As the air cools, water vapor condenses into tiny particles called cloud condensation nuclei to form cloud droplets Formation of cloud elements (Droplets/Ice crystals) For droplets, hygroscopic nuclei, small particles (0.1-10μm) having affinity for water must be available in upper troposphere. For ice crystals, Freezing Nuclei are required. Source of condensation nuclei are particles of sea salts, products of sulphurous and nitric acid. Source of freezing nuclei are clay minerals, usually kaolin, silver iodide etc. Growth of Droplets: Cloud droplets grow by colliding and coalescing with other droplets or by ice crystals growing through the Bergeron-Findeisen process. The Bergeron-Findeisen process is crucial in forming precipitation in cold clouds. It involves ice crystals and supercooled water droplets coexisting, with water vapor more likely to deposit onto ice crystals than remain as vapor or condense into droplets. This causes ice crystals to grow at the expense of the evaporating water droplets, eventually becoming heavy enough to fall as precipitation like snow or rain. This process is particularly important in mid-latitude and polar regions. The growth of cloud elements is essential for precipitation. One key process is the coalescence of cloud droplets, where smaller droplets join larger ones due to different fall velocities. Larger droplets fall faster and collide with smaller ones, increasing the size of cloud droplets, ultimately leading to precipitation. Another important process is the coexistence of cloud droplets and ice crystals. In mixed-phase clouds, water droplets evaporate and condense onto ice crystals because the saturation vapor pressure over ice is lower than over water. This causes ice crystals to grow and fall, further enlarging as they collide with more water droplets, contributing to precipitation. Growth of cloud elements For occurrence of precipitation over an area it is necessary that cloud elements must be grown in size to overcome Precipitation: When these droplets or ice crystals become heavy enough, they fall to the ground as precipitation (rain, snow, sleet, or hail) Measurement of Precipitation 1. Amount of precipitation 2. Intensity of precipitation 3. Duration of precipitation  4. Arial extent of precipitation Measurement of precipitation (Rain and Snow) can be done by various devices. These measuring devices and techniques are; Rain Gauges are essential tools for measuring liquid precipitation. They come in various types: Standard Rain Gauge: A graduated cylinder collects rain, and the water level is read directly. Tipping Bucket Rain Gauge: Funnels rain into a small bucket, which tips and triggers a counter when full, measuring rainfall incrementally. Weighing Rain Gauge: Measures the weight of collected water to calculate precipitation. Float Recording Gauges Float recording gauges measure rainfall by recording the rise of a float as it captures increasing amounts of water. Some gauges require manual emptying, while others automatically siphon out the water; the float is often made of oil or mercury and can be affected by freezing conditions. Optical Rain Gauge: Uses laser or infrared beams to detect raindrops and measure the amount and intensity of rainfall. Other Gauges: Snow Gauges - A snow gauge is a type of instrument used to measure the solid form of precipitation. Radars Measurements A weather radar is a type of radar used to locate precipitation, calculate its motion, estimate its type (rain, snow, hail, etc.), and forecast its future position and intensity. Weather radars are mostly Doppler radars, capable of detecting the motion of rain droplets in addition to the intensity of the precipitation. Both types of data can be analyzed to determine the structure of storms and their potential to cause severe weather. Satellites - A weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. These meteorological satellites, however, see more than clouds and cloud systems, like other types of environmental information collected using weather satellites. Scratching of snow packs Water equivalent in snow packs