The greenhouse effect

The greenhouse effect

We are learning how to:

• explain climate change in terms of human activity heat radiation from layer of greenhouse gases re-radiated in all directions

• explain the greenhouse effect.

Greenhouse gases are gases that can absorb and emit heat radiation. The main greenhouse gases in the atmosphere, as far as global warming is concerned, are water vapour, carbon dioxide, methane and ozone.

Many scientists believe that global warming is caused by increasing concentrations of greenhouse gases in the atmosphere. This increase is the result of human activities.

The increase in concentrations of greenhouse gases in the atmosphere is commonly called the greenhouse effect because these gases have a similar effect to the glass roof and sides of a greenhouse. Heat becomes trapped in the greenhouse causing the temperature to rise.

Atmosphere

FIG 8.3.1 The greenhouse effect

heat radiation from surface of Earth back out into the atmosphere heat radiation is absorbed by the layer of greenhouse gases in the atmosphere heat from the Sun

The greenhouse effect should more correctly be called the enhanced greenhouse effect. The greenhouse effect has existed as long as the Earth has had an atmosphere. Without the greenhouse effect, Earth would never have become warm enough to support life as we know it.