Wind is caused by the uneven heating of the Earth's surface and is always named based on the direction it is blowing from, such as a north wind. There are two main types of winds: local winds that affect small areas and global winds that circulate across continents. Local winds include sea breezes and land breezes, which occur when air over land or water is heated and cooled at different rates, causing circulations. Global winds blow steadily in the same direction due to the Coriolis effect and include jet streams, fast currents of air in the upper troposphere. Moisture in the air, measured by humidity and dew point, can condense to form clouds and precipitation including rain.

1. Chapter 16 Wind and water in our atmosphere

2. Wind is caused by the unequal heating of the earth!

3. Important fact! Wind is always named by where it is coming from! It is called a NORTH wind because it is moving from the north to the south. What would a wind be named if it is blowing from Georgia to Florida?

4. Two main types of wind: Local - small area Global - across continents

5. Local winds Most often noticed at the beach!

6. Land heats up faster than water. Warm air over land rises. Air over water moves to shore. Would occur during the day. Named a SEA breeze because it comes from the sea. http://www.coolweather.co.uk/

7. Land cools off faster than water. Warm air over water rises. Cool air from land takes its place. Would occur at night. Called a LAND breeze because the wind is coming from the land. http://www.coolweather.co.uk/

8. Look at these two diagrams. Can you tell which is the land breeze and which is the sea breeze? Video on beach convection

9. Global winds 1. Blow steadily from the same direction all the time. 2. The path is curved because of the Coriolis Effect. http://cimss.ssec.wisc.edu

10. Jet Stream In the upper troposphere. Very fast 200-400 kmh Go completely around the earth.

11. Notice that the jet stream does not stay the same every day. But it is always there!

12. jet stream

13. Notice on this weather map in motion how the rain moves toward the east over time.

14. Humidity Is a measure of how much water vapor is in the air. It is measured in a percent using a psychrometer . More humidity means more clouds and more likely chance of precipitation.

15. Dew point is the temperature when water vapor condenses to a solid or liquid This forms clouds!

16. http://www.wildlandschool.net Clouds from when the water vapor reaches the dew point. Remember that as you go up in the troposphere, the temperature decreases. Dew point

17. If the dew point temperature is the same as the air temperature on the ground, fog forms!

18. Precipitation Any form of H 2 O that falls from clouds and reaches the earth's surface.

19. The term rain is restricted to drops of water that fall from a cloud and have a diameter of at least 0.5 millimeter . Drizzle and mist have smaller droplets . The most common form of precipitation is rain.

20. Drizzle droplet raindrop Mist droplet Cloud droplet Droplets come in many sizes

21. As water vapor collects into larger and larger droplets, gravity will cause them to fall to the ground as rain, sleet, hail, or snow.

22. Clouds Form when water vapor condenses to form drops of liquid water or ice crystals. There are three main types of clouds.

23. Cirrus – high, thin, feathery clouds Made of ice crystals

24. Cumulus – round, puffy clouds Indicate fair weather

25. Stratus – flat layer of clouds. Often have rain.

26. Cumulonimbus clouds often produce bad weather (lightning and hail) Nimbus means rain. Notice that it is getting flat on the top. That means the top of the cloud has reached the top of the troposphere and cannot go any higher. http://www.colby.edu/

27. Any questions?