1. Local and Global Wind Systems
S6E4c. Develop a model demonstrating the interaction between unequal heating and the rotation of the Earth that causes local and global wind systems.

2. What is wind?
Wind is moving air and is caused by differences in air pressure within our atmosphere.
High pressure always moves towards low pressure
The greater the difference in wind, the faster the air flows
Wind is described using direction and speed
Local winds are named for where they originate (begin)

3. Types of Wind Local Winds Global Winds
Smaller wind systems that affect local weather
Sea Breezes and Land Breezes
Mountain and Valley Breezes
Larger wind systems that determine major weather patterns for the entire planet

4. Let’s Review Air Pressure
Air pressure is the measure of the force with which air molecules push on a surface
Air pressure is greatest at the surface of Earth because there are more air molecules pushing down from above

5. As you increase in altitude, air pressure decreases.
There are fewer air molecules above you to push down, so the force will be less
This Photo by Unknown Author is licensed under CC BY-SA

6. Air Pressure is dependent on density
More dense air will have higher air pressure – there are more molecules in a given space to push down on you
Less dense air will have lower air pressure – there are fewer air molecules to push down on you

7. Temperature and Air Pressure
Warm air is less dense than cold air, so warm air has lower air pressure and cold air has higher air pressure.
Molecules in cold air are moving slowly and are close together = high air pressure
Molecules in warm air are moving fast and are spread further apart = low air pressure

8. Partner Share
Land heats and cools faster than water. How does this affect wind?

9. Sea Breeze High Pressure 65°F 85°F Low Pressure
Look at the temperatures of the land and the sea in this diagram.
Where is the low and high pressure?
Which direction would the wind blow?
Explain
High
Pressure
Sea Breeze
The wind will blow from the sea to the land because it is a cooler temperature which means higher pressure and winds flow from high pressure to low pressure.
65°F
85°F
Low Pressure

10. Land Breeze 65°F 55°F Low Pressure High Pressure
At night when the earth’s surface is no longer being heated by the sun, the land cools much more rapidly than ocean water. What happens to the wind?
Land Breeze
The wind changes direction, now originating from the land since the temperature is lower than that of water. Pressure still moves from high to low pressure.
65°F
55°F
Low
Pressure
High
Pressure

11. Land Breeze
Sea Breeze

12. Mountain and Valley Breezes
Mountain Breeze (Night)
Valley Breeze (Day)
The cool air moves down the slopes into the valley.
During the day, the sun warms the air on the slopes creating a valley breeze. The cool air pushes the warm air up the slopes

13. Global Winds Created by unequal heating of Earth’s surface
Warm Air = less dense  warm air rises at the equator
Cool Air = more dense  cool air sinks at the poles
The movement of air between the poles produces patterns of circulation called global winds
The circular motion of the winds is created by the Coriolis Effect

15. Use this diagram to fill in your notes

16. Local and Global Winds http://studyjams. scholastic
Local and Global Winds and-climate/air-pressure-and-wind.htm