1. Earth and Space Science Chapter 24
Weather
Earth and Space Science
Chapter 24

2. No Place Like Kansas

3. Why is meteorology so important?

4. Why is meteorology so important?

5. Air Pressure
Unequal heating of Earth’s surface causes differences in air pressure
Areas near the equator receive more sun, so a low-pressure belt is created
Cold air near the poles causes high-pressure centers
Differences in air pressure create wind patterns

6. How Air Moves
Air moves from areas of high pressure to areas of low pressure
Temperature and pressure differences on Earth’s surface create three wind belts in the Northern Hemisphere and three wind belts in the Southern Hemisphere
The Coriolis effect occurs when winds are deflected by Earth’s rotation also influences wind patterns

7. Wind Belts

8. Air Masses Classified according to their source regions
Air masses that form over the ocean are called maritime
Two types are maritime tropical and maritime polar
Air masses that form over the land are called continental
Two types are continental polar and continental tropical

9. Air Masses of North America
Four main types:
cP- continental polar (cold and dry)
mP- maritime polar (cold and moist)
cT- continental tropical (warm and dry)
mT- maritime tropical (warm and moist)

10. Fronts
Cold and warm air masses usually don’t mix because of the density
A boundary called a front forms between air masses

11. Cold Front
The front edge of a moving mass of cold air that pushes beneath a warmer air mass like a wedge

12. Warm Front
The front edge of advancing warm air mass that replaces colder air with warmer air

13. Stationary Front

14. 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

15. Weather Instruments
Thermometer- Air Temp.
Barometer- air pressure

16. Weather Instruments
Anemometer- wind speed
Wind Vane- wind direction

17. Weather Instruments Radiosonde- atmospheric conditions
Radar- reflected radio waves velocity and location

18. Weather Instruments
Weather satellites collect important information about the atmosphere.

19. Forecasting the Weather
Predicting the weather has challenged people for thousands of years.
People in many early civilizations attributed weather conditions to the gods.

20. Weather Forecasting
We now use the National Weather Service that exchanges information with other nations because many weather events start beyond the US.

21. Global Weather Monitoring
World Meteorological Organization
Sponsors World Weather Watch so that stations around the world may communicate information about the weather rapidly

22. Weather Maps
Meteorologists input data into computers to create weather models.
Four types of forecasts:
Daily forecasts: 48 hour
Extended forecasts: 3-7 days
Medium range forecasts: days
Long-range forecasts: Covers monthly and seasonal periods

23. Extended Forecast

24. Severe Weather
When meteorologists forecast severe weather, they issue:
Warnings- severe weather has been spotted or is expected within 24 hrs
Watches- conditions are ideal for severe weather

25. Controlling the Weather
The most researched method for controlling the weather is called cloud seeding
Particles are added to clouds to cause clouds to precipitate
It has been somewhat successful with precipitation

26. Weather Symbols

27. Clouds

28. Clouds
Cirrus clouds- are composed of ice crystals and have the highest altitude
Cirrocumulus are rare high altitude clouds
Cirrostratus are a high, transparent veil across the sky (may form a halo on the sun or moon)

29. Clouds
Cumulus Clouds- low- altitude, billowy clouds that look like cotton balls
Cumulonimbus- thunderheads
Altocumulus clouds- if the base of the cumulus cloud begins at middle altitudes
Stratocumulus clouds- low clouds that are a combination of stratus and cumulus

30. Clouds Stratus clouds- have a flat uniform base Nimbostratus- rain
Altostratus- little precipitation