If greenhouse gas molecules were enlarged, this would be their general shape.
The Greenhouse Effect
A planet's atmosphere can sometimes serve as a trap of radiant heat and energy. A photon of energy can enter, but cannot easily find its way out again, somewhat like a pinball in a pinball machine.
Certain molecules of air, called greenhouse gases, interact with energy by absorbing and re-emitting the energy. These molecules typically re-emit the energy back into the atmosphere, where it is often absorbed by another greenhouse gas molecule. Greenhouse gases include water vapor, methane, ozone, nitrous oxide, and carbon dioxide.
This feature of atmospheres is beneficial because the re-emitted energy maintains the temperature of the atmosphere, the way a greenhouse maintains warm temperatures inside the greenhouse. The greenhouse effect also helps maintain even temperatures from day to night.
An atmosphere that contains greenhouse gases can have a powerful greenhouse effect. Without its atmosphere and greenhouse gases, the surface of the Earth would be as cold as the surface of Mars. The presence of too many greenhouse gases can cause the temperature to increase out of control, however. Such is the case with the atmosphere of Venus.
Earth's greenhouse effect is growing stronger as the amount of greenhouse gases in the atmosphere increases. The additional greenhouse gases come mainly from burning of fossil fuels, which releases the gases and other air pollutants into the atmosphere. A stronger greenhouse effect is causing Earth's climate to warm.
Last modified February 1, 2010 by Lisa Gardiner.
You might also be interested in:
Most things around us are made of groups of atoms bonded together into packages called molecules. The atoms in a molecule are held together because they share or exchange electrons. Molecules are made...more
Less than 1% of the gases in Earth's atmosphere are called greenhouse gases. Even though they are not very abundant, these greenhouse gases have a major effect. Carbon dioxide (CO2), water vapor (H2O),...more
Methane is gas that is found in small quantities in Earth's atmosphere. Methane is the simplest hydrocarbon, consisting of one carbon atom and four hydrogen atoms. Methane is a powerful greenhouse gas....more
The Ozone Hole. The Ozone Hoax. Pollution. Skin Cancer. The topic of ozone makes headlines on a regular basis, but why does a single molecule merit such media coverage? How important is the ozone in our...more
Carbon dioxide is a colorless and non-flammable gas at normal temperature and pressure. Although much less abundant than nitrogen and oxygen in Earth's atmosphere, carbon dioxide is an important constituent...more
Energy from the Sun can enter the atmosphere, but not all of it can easily find its way out again. This is a natural process called the greenhouse effect. Without any greenhouse effect, Earth’s temperature...more
What do smog, acid rain, carbon monoxide, fossil fuel exhausts, and tropospheric ozone have in common? They are all examples of air pollution. Air pollution is not new. As far back as the 13 th century,...more