1. Weather
Chapter 24

2. Weather
Weather: is the condition of the atmosphere at a particular time.
Air moves from areas of high pressure to areas of low pressure. There is a general worldwide movement of surface air from the poles toward the equator.

3. Weather
Air Mass: a large body of air throughout which temperature and moisture content are similar
Air masses are classified according to their source regions. (Continental, Maritime, Tropical, Polar)

4. Weather
Continental: dry
Maritime: moist
Tropical: warm
Polar: cold

5. Weather Fronts Front: a boundary between air masses
For a front to form, one air mass must collide with another air mass.

6. Weather Fronts
Cold Front: the front edge of a moving mass of cold air that pushes beneath a warmer air mass like a wedge

7. Weather Fronts
Warm Front: the front edge of advancing warm air mass that replaces colder air with warmer air

8. Weather Fronts
Stationary Front: a front of air masses that moves either very slowly or not at all

9. Weather Fronts
Occluded Front: a front that forms when a cold air mass overtakes a warm air mass and lifts the warm air mass off the ground and over another air mass

10. Weather Fronts
Midlatitude Cyclone: an area of low pressure that is characterized by rotating wind that moves toward the rising air of the central low-pressure region

11. Severe Weather
Thunderstorms: a usually brief, heavy storm that consists of rain, strong winds, lightning, and thunder

12. Severe Weather
Lightning: when clouds discharge electricity. The released electricity heats the air, and the air expands rapidly and produces the loud noise known as thunder.

13. Severe Weather
Hurricane: a severe storm that develops over tropical oceans and whose strong winds of more then 120 km/h spiral in toward the intensely low-pressure storm center

14. Severe Weather
Hurricane: a severe storm that develops over tropical oceans and whose strong winds of more then 120 km/h spiral in toward the intensely low-pressure storm center

15. Severe Weather
Hurricanes are the most destructive storms that occur on Earth. The most dangerous aspect is the rising sea level and large waves called a storm surge. (Typhoon- South Pacific)

16. Severe Weather
Tornado: a destructive, rotating column of air that has very high wind speeds and that maybe visible as a funnel-shaped cloud.
Smallest, most violent, shortest-lived storm.

17. Severe Weather
Tornados form when a thunderstorm meets high-altitude horizontal winds. These winds cause the rising air in the thunderstorm to rotate.

18. Weather Instruments
Thermometer: an instrument that measures and indicates temperature
Barometer: an instrument that measures atmospheric pressure

19. Weather Instruments
Anemometer: an instrument used to measure wind speed
Wind Vane: an instrument used to determine direction of the wind

20. Weather Instruments
Radiosonde: a package of instruments that is carried aloft by balloons to measure upper atmospheric conditions, including temperature, dew point, and wind velocity

21. Weather Instruments
Radar: radio detection and ranging, a system that uses reflected radio waves to determine the velocity and location of objects

22. Forecasting the Weather
Station Model: a pattern of meteorological symbols that represents the weather at a particular observing station and that is recorded on a weather map