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

2. Meteorology Test Review

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

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

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

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

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

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

9. Temperature and Pressure Variation in the Atmosphere

10. 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

11. 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

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

13. 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.

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

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

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

17. Stratus clouds:
Clouds that form in layers
Cover large areas

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

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

20. 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.

21. 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.

22. Global Wind Systems
Polar Easterlies- winds that blow from east to west between degrees latitude in both hemispheres.
Westerlies- The wind belt found between 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

23. 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

24. Fronts
Front- An area in which two airmasses meet

25. 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

26. 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

27. 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

28. 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

29. 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

30. Weather Maps
Station Model

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

32. 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

33. 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

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

35. 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.

36. “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

37. 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 mph.
Hurricane/typhoon – maximum winds 74mph or higher.

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

39. Saffir-Simpson Scale