Winds

1. Winds

2. What is wind? • Answer: Winds are caused by differences in air pressure.

3. What causes wind? • Answer: Most differences in air pressure (wind) are caused by the unequal heating of the atmosphere.

4. What causes the most differences in air pressure that causes wind? • Answer: Convection currents form when an area of Earth’s surface is hearted by the sun’s rays. Air over the heated surface expands and becomes less dense. As the air becomes less dense, its air pressure decreases. If a nearby area is not heated as much, the air above the less-heated area will be cooler and denser. The cool, dense air with a higher pressure flows underneath the warm, less dense air. This forces the warm air to rise.

5. How are winds described? • Answer: Winds are described by their direction and speed.

6. How are winds named? • Answer: The name of a wind tells you where the wind is coming from. For example: a south wind blows from the south toward the north. A north wind blows to the south.

7. Watch the demonstration • The fan is the wind source (dah!) • The wind vane is the straw arrow. • The “tail” is larger than the point • Note that when the wind blows, the point is in the wind, indicating the direction FROM which the wind is blowing.

8. What is an anemometer? • Answer: • An instrument used to measure wind speed.

9. What is a wind vane? • Answer: An instrument to determine wind direction. The wind swings the wind vane so that one end points INTO the wind.

10. What is “wind-chill factor?” • Answer: The increased cooling a wind can cause. The wind blowing over your skin removes body heat. The stronger the wind, the colder you feel.

11. Local winds • Answer: Local winds are the winds that blow over short distances. They are caused by the unequal heating of Earth’s surface within a small area. They only form when large scale winds are weak.

12. 1. Warm air over land rises 2. Sea Breeze moves inland 3. Clouds develop aloft and move seaward 4. Upper level return land breeze 5. Cool air aloft sinks over water 6. Sea Breeze blows over the land

13. 1. Cool air over land sinks • 2. Land Breeze moves out over water • Relatively warmer water heats air which then rises • 4. Upper level return sea breeze • 5. Cool air over land sinks

14. What are global winds? • Answer: The winds that blow steadily from specific directions over long distances.

15. How are global winds like local winds? How are they different? • Answer: Like local winds, global winds are created by the unequal heating of Earth’s surface. But unlike local winds, global winds occur over a large area.

16. How do global winds develop? • Answer: Temperature difference between the equator and the poles produce giant convection currents in the atmosphere. Warm air rises at the equator, and cold air sinks at the poles. Therefore air pressure tends to be lower near the equator and greater near the poles. This difference in pressure causes winds at Earth’s surface to blow from the poles toward the equator. Higher in the atmosphere, however, air flows away from the equator toward the poles. Those air movements produce global winds.

17. What is the Coriolis Effect? • The way Earth’s rotation makes winds curve is called the Coriolis effect.

18. HW: Draw the Global Winds in your NB.