Global Atmospheric Circulation

Global atmospheric circulation

• Warm air rises up into the atmosphere.

• It creates low pressure.

• Cool air sinks down to earth

• It creates high pressure.

• Wind is the movement of air from high to low pressure areas

• The 0° line of latitude is called the equator

Differential heating

• The sun’s rays do not heat the surface of the Earth evenly. This is because of the curvature of the Earth.

• At the equator, where the sun’s rays almost concentrated, it is warmer because of the higher surface temperatures and begins to rise as it is less dense than the surrounding air.

The Coriolis effect

• Coriolis effect is the deflection of moving objects (wind) when viewed in a rotating frame (Earth’s rotation)

• Earth’s atmospheric cell has prevailing winds associated with it. The Coriolis effect is the apparent of global winds, and ocean current curve as they move. The curve is due to the rotation of the Earth on its axis and leads to winds blowing diagonally.

GAC and the UK

The UK is loaded 55° north, just below the 60° north line of latitude. This puts the UK close to the boundary of cold polar air moving down from the north and warm sub tropical air moving up from the south. The boundary between these two air masses is unstable.

Weather

The short term changes in our atmosphere eg: temperature, rain and wind

Climate

Long term changes in the weather, usually over a 30 year period

Air mass

A large body of air with similar temperature, moisture and pressure

Extreme weather

Unusual, out of the ordinary, more severe than normal. It poses a risk to people and property