Atmosphere Composition and Layers

Atmosphere

• The atmosphere is composed of Nitrogen (N2) at 78.1%, Oxygen (O2) at 20.9%, and Argon (Ar) at 0.934%.
• Minor compounds make up ~0.07% of the atmosphere, including Carbon Dioxide (CO2), Neon (Ne), Helium (He), Krypton (Kr), and Hydrogen (H2).
• Aerosols, which are suspensions of fine solid particles or liquid droplets in air or another gas, are also contained in the atmosphere.
• Aerosols act as surfaces for water vapor condensation, leading to cloud and fog formation.
• Aerosols absorb, reflect, and scatter solar energy, influencing temperature and weather.
• Aerosols cause optical phenomena such as red and orange hues in the sunrise and sunset.
• Carbon Dioxide is the heaviest component of the atmosphere.
• Hydrogen Gas is the lightest component of the atmosphere.
• Nitrogen Gas is the most abundant component of the atmosphere.

Layers of the Atmosphere

• The troposphere's temperature decreases with altitude and extends 8-14 km above sea level.
• The troposphere experiences weather phenomena such as clouds, storms, and wind.
• Approximately 75% of the atmosphere's mass is contained in the troposphere, making it the most dense layer.
• The top of the troposphere is called the tropopause.
• The stratosphere's temperature is constant up to ~20 km, then increases with altitude due to ozone absorption of UV radiation, reaching up to 50 km.
• The stratosphere contains the ozone layer, which absorbs harmful UV radiation.
• Airplanes fly in the lower stratosphere due to stable conditions.
• The top of the stratosphere is called the stratopause, where temperature increase stops.
• Jet streams flow near the border between the troposphere and stratosphere.
• The mesosphere's temperature decreases with altitude, reaching the coldest temperatures in the atmosphere (~ -90°C) at the mesopause, extending up to 85 km.
• Meteors burn up in the mesosphere, creating shooting stars.
• The mesosphere is the least explored layer due to difficult accessibility as it is too high for balloons and too low for satellites.
• The top of them mesosphere is called the mesopause and has the coldest temperatures in the atmosphere.
• The thermosphere's temperature increases with altitude, reaching over 1000°C and extending up to 600 km.
• Auroras (Northern and Southern Lights) occur in the thermosphere.
• Satellites and the International Space Station (ISS) orbit in the thermosphere.
• sparse air molecules in the thermosphere move rapidly but reduce heat transfer, meaning it would feel cold to humans.

Other Regions in the Atmosphere

• The ionosphere overlaps the mesosphere and the thermosphere.
• The ionosphere contains an abundant layer of electrons and ionized atoms and molecules.
• The ionosphere has three main regions without distinct boundaries that vary during the day and change of seasons
• The D Layer absorbs the most energetic radiation, hard x-rays
• The E Layer absorbs soft x-rays
• The F Layer absorbs extreme ultraviolet radiation (EUV)
• The regions are arranged by increasing height - D, E, F
• The D and E regions reflect standard AM radio waves, while the F region reflects radio waves with shorter lengths
• Visible light, radar, television, and FM wavelengths are too short to be reflected and are only possible through satellites.
• The exosphere is the upper limit of the atmosphere, extending from the top of the thermosphere to 10,000 km.
• The exosphere has very thin air and no clear-cut boundary where it fades away into space.

Factors Affecting the Atmosphere

• Air density refers to the mass of air per unit volume and plays a crucial role in understanding how the atmosphere behaves at different altitudes.
• Air density is highest near the Earth's surface because gravity pulls air molecules downward, causing them to cluster more densely.
• As altitude increases, the pull of gravity weakens, and thus the air becomes thinner, leading to a decrease in air density.
• Most atmospheric gases are concentrated near the surface, making the lower layers of the atmosphere denser compared to higher altitudes.
• Air pressure is the force exerted by air molecules as they move and collide with surfaces.
• The more air molecules in a space, the more collisions occur, resulting in higher pressure.
• Like air density, air pressure decreases with altitude.
• Near the Earth's surface, gravity pulls air molecules closer together, creating higher pressure.
• As altitude increases, air molecules spread out, leading to fewer collisions and lower pressure.

Motions of the Ocean: How Do Waves Form?

• When wind blows into the oceans, the energy from the wind is transferred to the receiving body of water through friction which drives the water to move, causing waves.
• The height of the ocean wave is controlled by wind speed: a stronger wind, transfers more energy to the water.
• The height of the ocean wave is controlled by duration of the wind: the longer the wind blows, the more energy builds up in the waves, allowing them to grow taller.
• The height of the ocean wave is controlled by distance that wind blows over the water: longer uninterrupted distance where the wind blows across the water's surface allows waves to accumulate more energy
• The wave height is the measured distance from crest to trough while wavelength is the distance between two adjacent crests/troughs.

Ocean Waves in the Surf Zone

• When ocean waves travel towards the shoreline, the circular orbital motion of the waves starts to feel the sloping ocean bottom.
• The first wave “feels the bottom” when the water depth equals half the wavelength.
• Friction with the seabed flattens the circular motion of the wave.
• As the wave moves into shallower water, the flattened orbital motion forces the wave upward as a result of the sloping ocean floor.
• As the wave moves into shallower water, this results in a gradual increase in wave height.
• When the wave becomes too steep, the crest topples forward, forming a breaker.
• The breaking wave releases energy as it crashes onto the shore.
• The area where multiple breakers form is called the surf zone, and the term surf refers to the collection of breakers in a specific area near the shore.

Wave Refraction and Longshore Current

• As ocean waves approach the shoreline, they often hit at an angle, rather than straight on, which causes the waves to bend as they interact with the ocean bottom.
• The leading part of the wave “feels the bottom” and slows down due to friction with the seabed.
• The rest of the wave, still in deeper water, continues moving at its original speed.
• This difference in speed creates the appearance of bending—the part of the wave that slows down appears bent, while the section still in deep water remains straight until it too reaches shallower depths and begins to bend as well.
• When waves wash up the shore, they move at an angle, carrying sand and sediments with them.
• As the water recedes (returns to the ocean), it flows straight down due to gravity, following the slope of the shoreline.
• This repeated zigzag motion of water and sediment along the shore creates a continuous flow of water parallel to the coastline, known as the longshore current.

Riptides or Rip Currents

• Rip currents or riptides are strong, narrow currents that flow away from the shore and back into deeper water.
• They form when water pushed onto the shore by breaking waves needs a way to return to the ocean.
• As waves break along the shoreline, they push large volumes of water towards the beach, creating an accumulation of water near the shore.
• Since more water is continuously pushed onto the shore, the excess water must return to the ocean.
• Instead of flowing evenly back, it often funnels into a narrow, fast-moving stream.
• The returning water rushes through a break in between sandbars or other obstacles, forming a fast-moving channel of water heading seaward.

Ocean Circular Patterns

• Upwelling is an ocean circulation process where deep, cold, nutrient-rich water rises to replace displaced surface water.
• This process is primarily driven by winds blowing parallel to the coastline, which push warm surface waters away from the shore.
• As surface water moves away, cold water from below the thermocline rises to take its place, bringing essential nutrients to the surface.
• The Coriolis effect, caused by Earth's rotation, influences the direction of these winds and currents, causing surface water to be deflected to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
• Upwelling commonly occurs along the west coasts of major continents, where prevailing winds push warm water toward the equator.
• Upwelling also impacts global climate, helps adjust tempteratures and affects the Earth's heat budget.

Thermohaline Circulation

• Thermohaline circulation, also known as the global conveyor belt, is a major ocean circulation process driven by differences in water temperature and salinity.
• Variations in temperature and salinity affect water density, causing cold, salty water to sink and warm, less dense water to rise.
• This circulation moves warm water in surface currents and cold water in deep currents, slowly but across larger distances.
• The process transports heat to colder regions, particularly near the poles, helping regulate global temperatures.
• Although Europe and Canada are on the same latitudes, Europe remains relatively warmer since the thermohaline circulation transports warm water from the tropics to Europe, while Canada lacking such a current, experiences much colder conditions.

Extreme Weather Conditions

• Insolation (Incoming Solar Radiation) is the amount of solar energy received by Earth at the top of the atmosphere which drives Earth's climate system.
• Absorption by the Ground: Around 51% of the insolation is absorbed by Earth's surface, heating it and this absorbed heat is then released back into the atmosphere as longwave radiation.
• Reflection and Scattering: Some solar radiation is reflected by clouds, ice caps, and the atmosphere, while some is scattered into different directions.

Seasons

• The tilt of Earth's axis (23.5 degrees) causes variation in sunlight received at different latitudes throughout the year.
• Uneven heating causes summer with more direct sunlight and longer days lead to warmer weather.
• Uneven heating causes winter where indirect sunlight and shorter days result in cooler weather
• An Equinoxes has Equal day and night (March and September).
• A solstices has the Longest and shortest days of the year (June and December).
• A Heliophanograph is a Instrument used to measure the number of hours of sunlight using a glass sphere that concentrates light on a cardboard, which burns according to the sun's intensity

Elements of Weather

• Weather refers to the atmospheric conditions at a specific place and time including: temperature, humidity, precipitation, wind, air pressure, and clouds.
• Temperature is the measure of the amount of heat stored in an object or the speed at which air particles move.
• The faster the particles move, the higher the temperature.
• Areas closer to the equator receive more sunlight makeing them warmer.
• Higher elevations have lower temperatures due to thinner air
• Temperature is highest in the afternoon when the sun is at its peak.
• Different seasons affect temperature variations due to the tilt of the Earth, making temperatures unstable.
• Coastal areas have more stable temperatures compared to inland regions.
• Temperature is Measured using a Minimum-Maximum (Min-Max) thermometer
• Humidity the amount of water vapor present in the air.
• Humidity influences how dry or moist the atmosphere feels.can be measured in grams per cubic meter (absolute humidity) or as a percentage (relative humidity).
• Absolute Humidity – The total mass of water vapor in a given volume of air, usually measured in grams per cubic meter (g/m³).
• Relative Humidity – The percentage of water vapor in the air compared to the maximum it can hold at a given temperature, as such warm air can hold more moisture than cold air.
• Humidity is Measured Using a Sling Psychrometer to give Two thermometer determinations of relative humidity
• The Static Psychrometer - Measures humidity based on temperature differences.
• Effects of Low humidity are: Higher evaporation rate and Drier air.
• Effects of High Humidity are: Low evaporation rate and More humid air.

Precipitation

• Precipitation is Any form of water, liquid or solid, that falls from the atmosphere to the Earth's surface.
• Precipitation is Measured in length or distance
• The Kinds of precipitation are: Rain, Freezing rain (Rains that fall as liquid but freeze on contact), Sleet (Melts then freezes again; hailstones), and Snow.
• Precipitation Varies based on biome
• Clouds are Visible masses of water droplets or ice crystals suspended in the atmosphere and are located in the troposphere.
• Clouds need these things to form, collection of minute water particles, Humidity, and Right temperature (dew point) Where the air reaches saturation air molecules.
• Cumulus clouds are Heap and Puffy
• Cirrus/Circo clouds are high up and wispy
• Stratus/Strato clouds are Spread out while flat/layered and smooth
• Nimbostratus/Nimbo clouds are Rain-bearing
• Cluods are identified using Clear (<10%), solated (10% - 25%), Scattered (25% - 50%), Broken (50% - 90%), Overcast (>90%).
• Clouds can also be classified based on their altitude/height (low/mid/high).
• Air Pressure is the force exerted by air molecules as they press down on Earth's surface.

Factors Affecting Air Pressure

• High temperature creates low air pressure, and vice versa; The mercury barometer follows this logic.
• Air pressure decreases with higher elevation due to fewer molecules.
• Moist air is lighter than dry air because water vapor molecules are less dense than oxygen and nitrogen molecules, lowering the pressure.
• Low Pressure Area (LPA) - Cyclone contains less air, making it a region of rising warm air.
• Air converges (moves inward) toward the center- of an LPA, creating clouds and precipitation.
• LPAs are Often associated with stormy weather, typhoons, and hurricanes
• High Pressure Area (HPA) - Anticyclone contains more air, leading to sinking motion in the atmosphere
• Air diverges (moves outward) from HPAs, preventing cloud formation
• HPAs are Associated with clear skies, dry weather, and calm conditions.
• Air moves from high pressure to low pressure, creating wind patterns.
• Pressure areas shift depending on the movement of the ITCZ.
• Pressure areas shift due to seasonal variations in heating, land-ocean temperature differences, and atmospheric circulation patterns.
• Differences between heat - Land heats and cools faster than oceans; in winter, continents cool, forming HPAs, while warmer oceans maintain LPAs but in summer, land warms, creating LPAs, while oceanic HPAs strengthen and move poleward
• Tilt of the Earth - near January, the Southern Hemisphere is tilted toward the Sun, making it warmer as such HPAs strengthen in the colder Northern Hemisphere, while LPAs form in the warmer Southern Hemisphere
• Near July, the Northern Hemisphere tilts toward the Sun, reversing the pattern
• Topography/Elevation - High-altitude areas like the Tibetan Plateau intensify HPAs in winter and LPAs in summer, driving monsoons; Higher elevation equates to Less pressure
• In January, the Southern Hemisphere is tilted toward the Sun, receiving more heat which warms the land, causing air to rise and creating Low-Pressure Areas (LPAs); at the same time, the Northern Hemisphere is in winter, with colder air sinking, forming High-Pressure Areas (HPAs)
• In July, the Northern Hemisphere is tilted toward the Sun, reversing the pattern with warmer temperatures causing LPAs to form over land, while the Southern Hemisphere cools down, leading to HPAs as air sinks over cooler regions

Wind

• Wind Moves/Rushes of air to forms on air currents from high-pressure areas to low-pressure areas due to differences in temperature and air pressure which is altered Earth's rotation and its topography causes it.
• Bocal Winds are short-distance winds influenced by temperature and pressure differences in specific areas.
• Breezes are gental to moderate wind caused by temperature differences between land and water
• Sea Breeze (Daytime) occur when Land heats up faster than water, Warm air over land rises, creating low pressure and Cool air from the sea moves in to replace it
• Land Breeze (Nighttime) occur when Land cools faster than water, Warm air over the sea rises, creating low pressure and Cool air from the land moves in to replace it

Breezes

• Valley Breeze (Daytime) occur when Sun warms mountain slopes faster than valleys and Warm air rises from the slopes, drawing cool air from the valley
• Mountain Breeze (Nighttime) occur when Slopes cool quickly at night and Cold, dense air sinks into the valley
• Monsoons are seasonal prevailing winds in the region of South and Southeast Asia.
• Amihan (Northeast Monsoon) occur from October/November to March/April where Winds blow from the northeast toward the Philippines, Cooler temperatures, light rain, and calm seas, especially in Luzon and the Visayas occur and the weatehr is Dry season with minimal typhoon activity
• Habagat (Southwest Monsoon) occur From May/June to Octoberwhere the Southwest to Northeast, carrying warm, moist air from the Indian Ocean and South China Sea occurs and has Heavy rainfall, high humidity, strong winds, and rough seas, leading to flooding, landslides, and frequent typhoons.

Global Wind Systems

• The Global wind systems are driven by the the movement of air from high-pressure zones at the poles to low-pressure zones at the equator however because Earth is round and tilted, this simple movement is altered by the Coriolis Effect
• Coriolis Affect causes the apparent shift of movement of fluids and the atmosphere which is caused by the Earth's rotation
• Coriolis Affect occurs since Earth rotates eastward, moving air curves instead of traveling in a straight line.
• Coriolis Affect cause In in the Northern Hemisphere, winds curves to the right, and In the Southern Hemisphere, winds curves to the left.
• Coriolis affect prevents the air from moving directly from high-pressure to low-pressure areas, but instead forming distinct global wind belts.
• Air Wises at the equator (low-pressure zone) and moves toward 30° latitude, causes the Coriolis affect to make the wind curve westward causing Tropical Cyclones
• Intertropical Convergence Zone (ITCZ) is a narrow belt of low pressure near the equator where the northeast and southeast trade winds converge.
• The ITCZ shifts north during May-October (aligning with the Habagat) and south during November–April (allowing Amihan to enter) which, in the Philippines, this occurrence results in the different effects of the Amihan and Habagat

Extreme Weather Conditions

• Extreme Weather Conditions are events that are beyond the usual weather patterns which is characterized by: Extreme values (either minimum or maximum) of unusual weather variables, Rare occurrence and Disastrous effects.
• In the Philippines, a common example of EWCs are tropical cyclones or typhoons while another related phenomenon is storm surges, which are frequent and commonly accompany tropical cyclones.
• StormTtropical cyclones
• The Saffir Simpson Scale is used to internationally classify Tropical Cyclones
• PAHASA(PHILIPPINES) also has a clissification of tropical cyclones using: tropical depression, Tropical Storm, Severe Tropical Storm, Typhoon, and Super Typhoon.
• Typhoons in the Philippines are estimated at approximately 19 to 20 storms that occur annually within the Philippine Area of Responsibility (PAR)
• Factors Influencing Storm Surges: Size of the TC - Larger systems disturb a wider oceanic area, Movement Speed, and Coastal Geography - Shallow coastlines and bays enhance surge height
• El Niño-Southern Oscillation (ENSO) are periodic shifts that occure in atmospheric and oceanic conditions in the Pacific Ocean, occurring every 3-4 periods.
• El Nino occurs where Trade winds weaken or reverse causing warm water to spread eastward toward South America thus causing heavier rainfall and flooding in Peru and Ecuador but leading to Westerdroughts that experiencde reduced cloud formation as such the
• Thermocline which is a transition layer deepens, reducing cold water upwelling In La Niña Winds strengthen, intensifying warm water flow west towards Asia and Australia allowing Cold water upwelling increases which increases Rainfall and the The thermocline becomes.Shallow increases.Nuetrient and increases flooding in the Western area.