1. Winds
What causes winds?

2. Air Pressure
Air pressure is the measure of the force with which air molecules push on a surface
The air pressure is strongest in the Troposphere because of gravity

3. Wind Wind is the movement of air.
Winds are caused by differences in air pressure. (Cause of Wind)
Winds move from areas of high (cold air) pressure to areas of low (warm air) pressure
Differences in air pressure is caused by differences in the temperature of the air- caused by unequal heating of the Earth

4. Why is the Earth Unequally Heated
The Earth is unequally heat because it is titled on its axis. More of the sun’s direct rays hit the equator making the temperature at the equator warmer and the air less dense creating areas of low pressure (L)
The tilt of the Earth on its axis causes seasons on the Earth

5. Differences in air pressure are caused by unequal heating of the Earth.
Cool air has higher air pressure so it flows underneath (sinks) the warm, less dense air.
A B C.

6. Rising Air at the Equator
Because the Earth is tilted on its axis, the equator receives more direct solar energy from the sun.
Air at the equator is warmer than any where else on Earth . This less dense warm air rises creating areas of Low Pressure (L)

7. Sinking Air at the Poles
At the poles, the air is colder and denser than surrounding air, so it sinks. Creating areas of high pressure (H)

8. Why does warm air cause areas of low pressure?
Warm air causes areas of low pressure (L) because the air is less dense than the surrounding air and it rises

9. Why does sinking cold air cause areas of high pressure?
Sinking cold air causes high pressure (H) because sinking air presses down on the air beneath it.

10. Coriolis Effect
The apparent curving of path of winds and ocean currents due to the Earth’s Rotation
Winds in the Northern Hemisphere curve east.
Winds in the Southern Hemisphere curve west

11. Global Winds
The combinations of convection cells and the Coriolis Effect produce patterns of air circulation called global winds

12. Local Winds
Winds that blow over short distances and are caused by unequal heating of Earth’s surface within a small area.

13. Sea Breeze- (Day)
Sea Breeze – a wind that blows from an ocean or lake onto land. Air moves from areas of High Pressure (H) to areas of low Pressure (L)

14. Land Breeze-Night
Land Breeze – the flow of air from land to a body of water. Air moves from areas of high pressure (H) to areas of Low pressure (L)

15. Measuring Wind direction
A wind vane measures wind direction.
The name tells where the wind is coming from.
i.e. – north wind blows from the north to the south.

16. Wind speed
An anemometer measures wind speed.

17. Wind-chill factor
The wind-chill factor is the increased cooling that a wind can bring.