Podcast
Questions and Answers
What is the primary climate type of the Philippines?
What percentage of incoming solar radiation is absorbed by the Earth's surface?
Which law describes the amount of energy emitted based on temperature?
What primarily drives the atmospheric and oceanic circulation responsible for weather and climate?
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What is the role of atmospheric longwave radiation?
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What percentage of incoming solar radiation is reflected back to space?
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Which of the following processes is primarily driven by the energy available at the Earth's surface?
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What comprises 'incoming longwave radiation' in the context of radiation balance?
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What characterizes the rainy season in the Philippines?
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Which type of monsoon is known for bringing cool, dry air to the Philippines?
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What defines the Intertropical Convergence Zone (ITCZ)?
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During which months does the cool dry season occur in the Philippines?
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How many tropical cyclones typically enter the Philippine Area of Responsibility (PAR) each year based on historical data?
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Which instrument is used to measure global solar radiation, including both direct and diffuse components?
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What do easterly waves generally propagate?
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What is the primary climatic factor that varies across regions in the Philippines?
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What conditions do trade winds create in the Philippines?
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What is the main reason for the decommissioning of tropical cyclone names?
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What is the mean annual temperature of Baguio, located at an elevation of 1,500 meters?
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Which thermometer is known for expanding or contracting based on temperature changes?
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Which months represent the coolest and warmest temperatures in the Philippines?
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What is the primary effect of evaporation on the surrounding air?
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How is wind direction indicated?
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What is a wind rose used for?
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In what manner does cloud cover affect Earth's surface temperatures?
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Which of the following correctly defines climate variability?
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What is one consequence of high wind speeds near the surface?
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How does the shape of the wind speed profile change with height?
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What environmental factor can affect the rate of evaporation significantly?
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Which city receives the least amount of rainfall in the Philippines?
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What is the average range of mean annual rainfall in millimeters?
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How does atmospheric pressure change with altitude?
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Which month shows the highest average relative humidity in the Philippines?
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What happens to the amount of oxygen available as atmospheric pressure decreases?
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Which of the following is NOT a way to express atmospheric moisture content?
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How does high relative humidity affect plants?
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What typically occurs when a low-pressure system moves into an area?
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Study Notes
Course Information
- Course Title: ABEN 55 - Hydrometeorology
- Instructor: Engr. Melrose M. Salona
Daytime Duration Graph (Manila, Philippines 2024)
- Shows the changing length of daylight throughout the year starting in March, culminating in Summer Solstice, and terminating in the Winter Solstice in September
- Displays the 12-hour daytime duration point on September 30
- Graph shows longer nights in the months leading up to September's equinox and successively shorter days thereafter
Global Temperature Changes from Volcanic Eruptions
- Volcanic eruptions cause short-term climate changes.
- The 1991 eruption of Mount Pinatubo ejected significant amounts of volcanic material into the stratosphere.
- This led to a substantial release of sulfur dioxide, which became sulfuric acid aerosols.
- These aerosols remained in the stratosphere for years, blocking solar energy from reaching Earth's surface.
- This phenomenon caused a temporary global cooling effect.
- Volcanic eruptions can cause global cooling rather than global warming, disrupting weather patterns and temperatures.
Climate in the Philippines
- Factors like topography, location, trade winds, ITCZ, easterly waves, monsoon winds, fronts, and tropical cyclones influence the climate.
- Topography and location result in varied climatic conditions and orographic rainfall.
- Two main seasons based on rainfall and temperature: rainy season in June-November and dry season (Dec-May) with subsections of cool and hot dry season
- Philippine geography has varied topographic features and locations leading to diversified climatic conditions.
Termination of the Northeast Monsoon (Amihan)
- The retreat of a high-pressure area over Siberia weakens Amihan.
- The strengthening of the North Pacific High shifts wind patterns.
- A transition to warm and dry season occurs.
- Isolated thunderstorms are possible but usually occur in afternoons/evenings.
- Ongoing El Niño likely to decrease rainfall, potentially leading to dry spells/droughts.
Onset of the Rainy Season
- Scattered rainshowers, thunderstorms, and Typhoon Aghon's passage indicate start of the rainy season.
- High chance of La Niña conditions increase the likelihood of above-normal rainfall.
- There can be breaks/periods with little to no rainfall during the monsoon season called monsoon breaks.
La Niña Alert
- Recent climate monitoring shows cooling sea surface temperatures (SST) in the central and eastern equatorial Pacific.
- A 70% chance of a La Niña forming in August-September-October (ASO) 2024, likely lasting until 2025 first quarter.
- This development triggers a La Niña alert.
- Potential increased risk for floods and landslides.
Habagat Season Termination (Southwest Monsoon)
- Southwest Monsoon (Habagat) season ends due to a weakening system over East Asia and changed weather patterns.
- Transition to the Northeast Monsoon (NE) season expected in subsequent weeks.
Climate Map of the Philippines
- Climate types in the Philippines are based on precipitation and temperature
- Types I-IV describe varying patterns: pronounced wet and dry seasons, lack of dry season, less pronounced, and very evenly distributed, respectively
Weather Elements
- Solar radiation
- Temperature
- Rainfall
- Pressure
- Humidity
- Wind
- Evaporation
- Cloud cover
Radiation
- Drives atmospheric and oceanic circulation, powering winds and storms
- Atmospheric circulation is primarily responsible for weather and climate.
- Solar energy is the ultimate energy source
- Transformed to electromagnetic waves.
- Includes a continuous spectrum of wavelengths from radio waves to gamma rays.
- Different wavelengths of solar radiation interact with the atmosphere and the surface in various ways.
Relationship Between Surface Temperature, Amount of Radiation, and Wavelengths
- Low temperatures cause a small amount of radiant energy.
- High temperatures cause a large amount of radiant energy.
Solar Radiation at Earth's Surface
- Powers the Earth's climate system.
- 51% of incoming solar radiation (SR) absorbed by Earth's surface, 19% absorbed and 30% reflected.
Earth's Global Energy Balance
- About 50% of incoming solar radiation absorbed by the surface.
- About 90% of outgoing longwave radiation absorbed by the atmosphere.
- Total outgoing infrared radiation 235 W (Watts)
Longwave Radiation
- Heat emitted as a result of absorbing solar radiation.
- Based on Stefan-Boltzmann Law.
- Atmospheric longwave radiation (RLW↓) is impacted by air temperature.
- Terrestrial longwave radiation (RLW↑) is influenced by Earth's surface temperature.
Radiation Balance Near the Surface
- Energy available at Earth's surface drives evapotranspiration and photosynthesis (among others)
- Incoming radiation includes SW and LW from sky and surrounding.
- Outgoing radiation includes SW reflected or transmitted by the surface and LW emitted by the surface.
Radiation-Measuring Instruments
- Pyrheliometer - measures direct solar radiation
- Pyranometer - measures global solar radiation (direct and diffuse)
- Pyrradiometer - measures total radiation (SW + LW)
- Pyrgeometer - measures longwave radiation
- Quantum (PAR) sensor - measures visible light (PAR)
Sunshine Duration
- The length of time the ground surface is irradiated by direct sunlight (without solar radiation data)
- Measured by Campbell-Stokes and Jordan sunshine recorders.
Temperature
- A measurement of kinetic energy.
- Response of any object to heat.
- Thermometers measure, using mercury, which expands and contracts based on heat change.
Temperature (Specific to the Philippines)
- Mean annual temperature is 26.6 °C excluding Baguio.
- Coolest month: January (25.5°C).
- Warmest month: May (28.3°C).
- Altitude impacts temperature.
- Baguio's mean annual temperature (1,500 meters) is 18.3 °C.
Variation in Temperature with Height
- Lapse condition – temperature decreases with height.
- Radiation temperature inversion – temperature increases with height.
Average Global Temperature Map
- Map showing global surface temperature averages.
Average Minimum & Maximum Temperature (Manila)
- Graph illustrating average minimum and maximum daily temperatures for Manila throughout the year.
Daily maximum and minimum temperatures (Quezon City)
- Graphs illustrating the maximum and minimum temperatures for Quezon City for a 25-day period
Highest Observed Heat Index (March 25, 2023)
- A table listing locations with the highest observed temperatures.
July 2023 State of the Climate (Hottest Month on Record)
- July 2023 was hotter than previously recorded months.
- Related to the warming global climate
Rainfall
- The most important climatic element in the Philippines.
- Rainfall distribution varies throughout the country.
- Moisture-bearing winds and mountain systems determine distribution patterns
- Mean annual rainfall varies from 965 to 4,064 millimeters
- Specific locations such as Baguio, Eastern Samar, and Eastern Surigao have high amounts of rainfall.
- Cotabato has the lowest recorded rainfall.
Precipitation Map (January 2010)
- Map showing global precipitation.
Average Monthly Precipitation (Manila)
- Graph showing average monthly precipitation in Manila.
Rainfall Measuring Instruments
- Tipping Bucket Rain Gauge and its recorder.
- 8-inch Standard Rain Gauge.
Pressure
- The weight of the air above a surface results in pressure.
- Low-pressure systems lead to cloudy conditions, wind, and precipitation, and high-pressure systems lead to fair, calm weather.
- Pressure decreases with altitude.
Humidity
- Amount of moisture/water vapor in the air.
- Air can hold a certain amount of water, dependent on its temperature.
- Philippines has a high relative humidity.
- Relative humidity is between 71 percent (in March) & 85 percent (in September).
- Highest humidity and temperature levels generally from March to May.
Role of Humidity in Plants and Animals
- Impacts drying capacity of air
- Influences transpiration rate of plants
- Affects phyto-pathogen growth
- Influences thermal comfort
- Primary source of water (dew)
Atmospheric Moisture Content
- Several ways to express atmospheric moisture content:
- Absolute humidity
- Mixing Ratio
- Specific Humidity
- Vapor Pressure
- Relative Humidity
- Dew-Point Temperature
- Wet-bulb Temperature Measurement of humidity involves using various instruments.
Wind
- Highly variable in time and space, direction and velocity.
- Wind speed decreases as it approaches the Earth's surface.
- Wind-speed profile (WS vs height) is logarithmic.
Wind Speed Instruments
- 3-cup anemometers
- Propeller vanes
- Hot-wire anemometers
- Sonic anemometers
Wind Direction
- Direction from where wind blows.
- Expressed in degrees (360°) or compass points (N, NE, etc).
Prevailing Wind
- Most commonly observed wind direction during a given time.
- Using a wind rose, one can determine the dominant wind patterns.
Evaporation
- Process of changing liquid water to water vapor.
- Transports water from Earth's surface to the atmosphere.
- Cooling process because it removes heat.
- Depends on air, temperature, wind speed, and cloudiness.
- Responsible for several weather phenomena.
Clouds
- Form at various atmospheric levels.
- Affect weather and climate patterns.
- Cloud type and amount impacts precipitation patterns.
- Influences surface temperatures by acting as an atmospheric layer.
Cloud Cover
- Sky cover (eighths of sky covered).
- Different levels of cloud cover.
Climate Change
- A trend in one or more climate variables.
- Marked by an increase/decrease of long-term average values during the observation period.
Climate Variability vs. Climate Change
- Variability: departures from long-term average.
- Change: long-term trend or shift in averages.
- Graph illustrating the difference
Historical Surface Temperature Variations
- Shows temperature changes at the Earth's surface over million years, last 10,000 years and in the last thousand years, illustrating periods of change and variability.
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Description
Test your knowledge on the climate and weather patterns of the Philippines. This quiz covers topics such as solar radiation, atmospheric circulation, and the unique seasonal characteristics of the region. Challenge yourself with questions about monsoons, cyclones, and the radiation balance.
