Heat Transfer and Winds

Heat is transferred in three ways

RadiationConductionConvection

Convection Currents

Warm air rises, then cools and become more dense

Cool air sinks back toward the ground

Heat is transferred mostly by convection within the troposphere

Winds are caused by differences in air pressure.

As air becomes less dense when it is heated, its air pressure decreases.

Cool, dense air with a higher pressure forces the warm air to rise.

Wind Direction

Wind direction is determined with a wind vane

The direction of the wind vane tells you where the wind is coming from

Wind speed can be measured

by an anemometer.

When wind blows over your skin, it removes body heat and makes you feel colder. The increased cooling a wind can cause is called the wind-chill factor.

Local Winds

Are caused by the unequal heating of Earth’s surface within a small area.

A sea breeze happens during the day when cool air moves from the sea to the land.

A land breeze takes place at night when cooler air moves from the land to the sea.

Global Winds

Are created by the unequal heating of Earth’s surface over a large area

Major global wind belts are the trade winds, the polar easterlies, and the prevailing westerlies.

Coriolis effect

Is the effect of Earth’s rotation on the direction of winds and currents.

Jet Streams

Bands of high-speed winds about 10 km above Earth’s surface.

Generally blow from west to east at speeds of 200 to 400 km/hr

They follow a wavy path