Investigation 9B

Key Question: How is convection responsible for the movement of air through the atmosphere??

Convection in Earth’s Atmosphere

9.2 Heat transfer

Thermal energy flows from higher temperature to lower temperature. This process is called heat transfer.

There are three ways heat flows: heat conduction, convection, and thermal radiation.

9.2 Heat transfer Heat conduction is

the transfer of heat by the direct contact of particles of matter.

Conduction occurs between two materials at different temperatures when they are touching each other.

Where is the heat energy conducted to and from in this system?

9.2 Thermal EquilibriumWhen both materials are at the same temperature, they are in thermal equilibrium.

No heat flows when objects are in thermal equilibrium.

9.2 Thermal conductors and insulators

Materials that conduct heat easily are called thermal conductors and those that conduct heat poorly are called thermal insulators.

Is a down coat a conductor or an insulator?

9.2 Convection Convection is the transfer of heat through

the motion of matter such as air and water.

The hot water at the bottom of the pot rises to the top and replaces the cold water.

9.2 Convection

Convection is mainly what distributes heat throughout a room.

9.2 Thermal radiation Heat from the Sun is

transferred to Earth by thermal radiation.

All the energy the Earth receives from the Sun comes from thermal radiation.

The higher the temperature of an object, the more thermal radiation it emits.

9.2 Thermal radiation Thermal radiation is also

absorbed by objects.

The amount of thermal radiation absorbed depends on the surface of a material.

Dark surfaces absorb most of the thermal radiation they receive.

Silver or mirrored surfaces reflect thermal radiation.

9.2 Heat transfer, winds, and currents

A thermal is a convection current in the atmosphere.

When a surface, like a road absorbs solar radiation, it emits energy as heat.

The warmed air molecules gain kinetic energy and rise.

Colder air is forced aside and sinks.

9.2 Thermal radiation

There are giant convection currents in Earth’s atmosphere.

The global wind patterns and Earth’s rotation also cause surface ocean currents to move in large circular patterns.

Needed: Efficient Buildings“Green” building design is the term used to describe architecture that is energy-efficient and environmentally friendly.