1 METEOROLOGY.pdf

METEOROLOGY Why is studying the weather important? Overview 1. Atmosphere 2. Heat Exchange Process 3. Global Circulation Patterns 4. Pressure Systems 5. Clouds 6. Thunderstorms 7. Frontal Systems 8. Weather Information Atmosphere ➢ Surrounds the Earth ➢ Held together by Gravity ➢ Mixture of gases ➢...

METEOROLOGY Why is studying the weather important? Overview 1. Atmosphere 2. Heat Exchange Process 3. Global Circulation Patterns 4. Pressure Systems 5. Clouds 6. Thunderstorms 7. Frontal Systems 8. Weather Information Atmosphere ➢ Surrounds the Earth ➢ Held together by Gravity ➢ Mixture of gases ➢ Medium in which we fly Layers of the Atmosphere Divided into layers based on temperature 1. Troposphere 2. Stratosphere 3. Mesosphere 4. Thermosphere 1. Troposphere o Ground level to 6mi / 33,000ft. o temperature decreases with height to -59deg. Celsius o Troposphere contains almost all the water vapor o Clouds and weather exist here o Vertical movement of air – warm air rising and cool air descending 2. Stratosphere o Tropopause to 160,000ft. o Relatively calm o Dry and clouds are rare o Temperature decreases to 0deg. o Location of the ozone layer – blocks sun’s harmful rays Properties of the Atmosphere - Density - Pressure - Humidity - Temperature 1 METEOROLOGY Density • Mass of air molecules in a given volume • Thickness of air Pressure • Force exerted by the weight of air molecules Temperature • Coldness or warmness of the air • Low = high pressure & density • High = low pressure & density Humidity • Amount of water vapor in the air • Water Vapor > Air molecules = Less Dense Air DENSITY PRESSURE TEMPERATURE Latent Heat INTERNATIONAL STANDARD ATMOSPHERE (ISA) Air is a perfectly dry gas Standard temperature at mean sea level: 15 °C Standard temperature lapse rate: 2°C per 1,000 ft. Standard pressure at mean sea level: 29.92 inHg Standard pressure lapse rate: 1 inHg per 1,000 feet. • Relative Humidity - how much water vapor is in the air compared to how much it can hold - reduce during the day and increase at night • Saturated Air – air that contains the maximum amount to water vapor it can hold • Unsaturated Air – air that is not holding as much water vapor as possible • Dew Point - temperature to which air must be cooled to become saturated with water vapor • Spread – difference between temp. & dew point Adiabatic Cooling Process • The process by which air cools 1. Parcel of air is heated 2. Expands 3. Density decreases 4. Weight decreases 5. Rises 2 METEOROLOGY Heat Exchange Process The Sun • Main source of energy on Earth Heat Exchange & Temperature Variation • Results in changes in weather Surface Heating & Cooling 1. Tilt of the Earth 2. Shape of the Earth 3. Land vs. Water 4. Cloud Cover Effects of Temperature • Buoyancy of Air Hot Air: Less Dense & Rises Cold Air: More Dense & Sinks • Pressure Pressure Gradient Force (PGF) - force that initiates wind • Wind - movement of air Advection: Horizontal Movement Convection: Vertical Movement 3 METEOROLOGY Wind Patterns 4