1. Wind Notes

2. Why Air Moves Wind is created by differences in air pressure
Bigger difference = faster wind
Caused by unequal heating of earth

3. Air The air by the equator is warm and rises
Low pressure
The air by the poles is cold and dense
High pressure
Wind will then travel from poles to equator
Move from area of high pressure to area of low

4. Pressure Belts Wind travels in small belt patters
It never travels too far because it will cool as it moves and sink back down
Moves at a about 30 degrees at a time or down the earth

5. Earth’s rotation affects wind direction
Without the earths rotation the global winds would flow directly from the poles to the equator.
Coriolis Effect
Influence of Earth’s rotation on objects that move over Earth.

6. The Coriolis Effect The wind does not travel perfectly north to south
Earth’s rotation causes wind to travel in a curved path

7. Coriolis Effect Global winds curve as Earth turns beneath them.
Northern Hemisphere
Winds curve to the right
Southern Hemisphere
Winds curve to the left
Only noticeable for winds that travel long distances.
Causes global winds to travel along 3 routes in each hemisphere
Routes are called global wind belts

8. Types of Wind Local wind Global wind Both caused by uneven heating
Sea Breeze
Land Breeze
Monsoon – Seasonal changes in wind
Global wind
Doldrums / Horse Latitudes
Easterlies / Westerlies
Jet Stream
Both caused by uneven heating

9. Global Winds The distance winds travel varies.
Sunlight is concentrated near the equator because it strikes the surface directly
The distance winds travel varies.
Some winds die out quickly
Global winds
Winds that travel long distances in steady patterns over several weeks
Caused by uneven heating between the equator and the north and south poles
Sunlight is more spread out near the poles because it strikes at a lower angle

10. Global Winds Continued
Near the equator concentrated sunlight heats the surface to a high temperature. Warm air rises, producing low pressure.
In regions closer to the poles, the sunlight is more spread out. The air above them is cooler and dense. Sinking dense air produces high pressure that sets global winds in motion.

11. Calm Regions Doldrums Horse Latitudes Low-pressure zones near equator
The rising, moist air produces clouds and heavy rain.
Horse Latitudes
High-pressure zones located 30 degrees north and south of the equator.
Clear and dry weather

12. Wind Belts Coriolis effect creates 3 wind belts in each hemisphere
Trade Winds
Blow from east. Move towards equator. Die out as they near the equator
Westerlies
Blow from the west. Move towards the poles. Brings storms across much of the U.S.
Easterlies
Blow from the east. Move towards mid-latitudes. Storms occur when cold air from easterlies meets the warm air of the westerlies.

15. Effects of Wind on Travel
How would wind effect travel?
Sailors used to dread traveling through the doldrums and the horse latitudes because there wasn’t enough wind.
To avoid the calm regions, sailors sought out global wind belts
Sailors rely on trade winds to get across the ocean

16. Jet streams flow near the top of the troposphere
Flow in upper troposphere
Travels west to east
Often moves at high speeds (greater than 124 mi/hr).
Form because Earth’s
surface is heated
unevenly.
Loop north and south

17. Jet Streams Each hemisphere has 2 jet streams Subtropical jet stream
Flow closer to poles in SUMMER
Polar jet stream
Has a strong influence of weather
Can pull cold air down from Canada or pull warm air up.
Strong storms form along its loops

18. Patterns of heating and cooling cause local winds
Some winds change daily in a regular pattern.
Blow within small areas
Land breezes and Sea breezes are similar but opposite.

19. Land Breeze / Sea Breeze

20. Land Breeze Wind blows from the land to the ocean
Happens during the Night
Land cools down causing it to have a low air pressure
Water maintains its temperature causing it to have a higher air pressure
Air will move from high pressure to low pressure
It will move from the land to water