What is the most abundant gas in the Earth’s atmosphere? Warm-up What is the most abundant gas in the Earth’s atmosphere?

Meteorology Test Review

Layers of the Atmosphere The atmosphere is a mixture of gases that surrounds the Earth.

Earth’s Atmosphere is 78% Nitrogen 21% Oxygen 1% Argon and Carbon Dioxide Ozone (O3) absorbs ultraviolet (UV) radiation from the sun

Thermosphere- The upper-most layer; Temperature increases as altitude increases.

Mesosphere- middle layer, temperature decreases as altitude increases Mesosphere- middle layer, temperature decreases as altitude increases. 50-80km

Stratosphere- the layer that contains the ozone layer- temp increases as altitude increases. 10-50km

Troposphere- lowest layer of the atmosphere; layer where we live and where all weather takes place.

Temperature and Pressure Variation in the Atmosphere

Heat Transfer Heat is the energy transfer from one object to another because of a difference in temperature Temperature is a measure of the average energy of the individual atoms/molecules in a substance

Heat transfer Conduction: transfer of heat energy through a solid object Radiation: transfer of energy through electromagnetic waves Convection: transfer of heat energy through movement of a liquid or gas

Wind Wind- the movement of air caused by differences in air pressure The greater the difference in pressure the faster wind moves

Humidity- The amount of water vapor in the air Relative humidity- is the amount of moisture in the air compared to what the air can "hold" at that temperature. Measured with a psychrometer.

Dew Point- the temperature at which a gas condenses into a liquid.

Clouds A cloud is a collection of millions of tiny water droplets or ice crystals.

Cumulus clouds: Puffy, white clouds that tend to have flat bottoms Indicate fair weather

Stratus clouds: Clouds that form in layers Cover large areas

Cirrus Clouds: Thin, feathery, white clouds Found at high altitude When they get thicker, it indicates a change in weather.

Alto- describes clouds at middle altitudes Cirro- describes clouds that form at high altitudes Nimbo- likely to produce precipitation

Causes of Weather Meteorology – the study of atmospheric phenomena Weather- is the condition of the atmosphere at a certain time and place Climate is the long term weather for a particular area.

Air masses Name Description c Continental Dry m Maritime Wet E Equatorial Hot T Tropical Warm P Polar Cold A Arctic Very Cold An air mass is a large body of air that takes on the characteristics of the area over which it forms.

Global Wind Systems Polar Easterlies- winds that blow from east to west between 60-90 degrees latitude in both hemispheres. Westerlies- The wind belt found between 30-60 latitude in both hemispheres Trade winds- Winds that blow northeast from 30 north latitude to the equator and that blow southeast from 30 degrees south latitude to the equator

Global Wind Systems Coriolis effect- deflection of particles to the right in the northern hemisphere and to the left in the southern hemisphere due to Earth’s rotation

Fronts Front- An area in which two airmasses meet

Fronts Cold Front- occur when a cold air mass runs into a warm air mass, forcing the warm mass to rise Warm Front- When warm masses run into cold masses and slowly displaces it

Fronts Stationary Front- Two air masses meet and neither advances; air masses “stall” Occluded Front – Cold air mass moves so rapidly that it overtakes a warm front

Pressure Systems High Pressure Systems - Air sinks, then hits the Earth’s surface and spreads out. Wind blows away from high pressure. Clockwise in N. Hemisphere Associated with fair weather

Pressure Systems Low Pressure System - Air rises, must be replaced. Wind blows toward center of low pressure Counter-Clockwise in N. Hemisphere Associated with clouds and precipitation

Weather Instruments Barometer- used to measure atmospheric air pressure. Thermometer- measures temperature Psychrometer – measures relative humidity Anemometer- used to measure wind speed. Windsock- an instrument to measure wind direction

Weather Maps Station Model

Weather Maps Isobars- lines that connect equal points of equal pressure

Thunderstorms Thunderstorm- a brief, heavy storm that consists of rain, strong winds, lightning and thunder Lightning- an electric discharge that takes place between two oppositely charged surfaces Thunder- the sound made by the thermal expansion of air

Stages of a Thunderstorm Cumulus stage - warm air rises upwards carrying moisture Mature stage- the precipitation falls rapidly to earth with downdrafts Dissipation- updrafts slow, storm has no more energy

A supercell is a self-sustaining, extremely powerful storm that has intense, rotating updrafts. Can lead to TORNADOES

Tornado- destructive rotating column of air visible to the naked eye Tornadoes are classified on the Enhanced Fujita Scale which ranks them according to wind speed, duration, and path of destruction.

“Tornado Alley” is located in the midwestern US “Tornado Alley” is located in the midwestern US. The midwest experiences the most tornadoes in the US

Tropical Cyclones A tropical cyclone is a large, rotating, low-pressure storm formed over warm, ocean water in the summer or fall. Types of tropical cyclones: Tropical depression – maximum winds 38 mph or less Tropical storm – maximum winds 39-73 mph. Hurricane/typhoon – maximum winds 74mph or higher.

Hurricanes are classified on the Saffir-Simpson scale from 1-5 based on wind speed, air pressure and potential for property damage.

Saffir-Simpson Scale