1. 4.3 Air Currents

2. Creates an area of High pressure
Warm Air
Rises
Low density
Creates an area of Low pressure
Cold Air
Sinks
High density
Creates an area of High pressure

3. Wind is the movement of air from an area of high pressure to an area of low pressure 2 types of wind are: Global wind patterns – affect all of Earth’s atmosphere and produces steady predictable winds. Local wind – affect smaller areas and change often

4. The amount of energy an area receives is affected by the Sun’s angle.
More sunlight reaches Earth’s surface at the equator than at the poles

5. Global Winds
Because warm air at the equator rises, it creates a low pressure area over the tropics.
The cooler air over the poles sinks and creates a high pressure area.

6. The Three cell Model – also known as Wind Belts
Scientists use a model that has three wind cells to describe the circulation patterns in Earth’s atmosphere.
The three global cells in each hemisphere create northerly and southerly winds

7. The Three Global Wind Patterns

8. The Coriolis Effect
The Earth’s rotation causes moving air and water to appear to move to the right in the Northern Hemisphere and the left in the Southern Hemisphere.

9. The Jet Stream
The narrow band of high winds near the top of the troposphere that can move at speeds up to 300 km per hour and are unpredictable
Flows around Earth from west to east making large loops to the north and south
Influences weather as they move cold air from the poles toward the tropics and warm air from the tropics toward the poles.

10. Sea Breeze – Day
On sunny days land heats up faster than water. The warm air over land rises and creates an area of low pressure.
The cooler air over the water sinks creating an area of high pressure.
The difference in temperature and pressure creates a cool wind that blows from the sea onto land

11. Land Breeze – Night
At night the land cools more quickly than the water. The warm air over the water rises creating a low pressure area.
The cooler air over land sinks and creates a high pressure area. This creates a breeze that moves from the land to the sea.