How do greenhouse gases trap heat from the sun?

Answer 1

Greenhouse gases absorb infrared electromagnetic radiation. As sunlight (mostly UV and visible light) heats the earth, longer wavelengths are radiated or emitted, i.e infrared light. Infrared active molecules, such as carbon dioxide and methane, absorb infrared light causing these molecules to vibrate. High concentrations of these vibrating molecules in the gaseous atmosphere provides for energy transfer (kinetic) due to vibrational collision. Because temperature is simply a measure of kinetic energy in matter, an increase in vibrational energy of gaseous molecules results in a rise in air temperature. The global result is an increase in measured average ambient temperatures.

Answer 2

Greenhouse gas molecules absorb infrared radiation. The energy they absorb from the Sun is not as important as what they block and reradiate from the Earth! Here is what happens:

Sunlight comes from the sun, goes through outer space, and enters the Earth's atmosphere. The light passes through the ozone layer, which filters out the UV and more energetic light, but at this point the greenhouse gases are not actually doing anything to the visible light. The light then strikes the Earth, and warms it. Any warm body will emit infrared (IR) radiation (this is due to something called the blackbody effect, and it is also how some night-vision goggles work). The IR radiation that is emitted by the Earth (again, because it was heated by sunlight) is what the greenhouse gases absorb.

Imagine for a moment that there were no greenhouses gases. The sunlight would hit the Earth, and the Earth would absorb that light and re-emit IR radiation. That IR radiation would just go out into space and the temperature of the Earth would be much higher in the daytime and lower at night (like the surface of the Moon). Instead, because there are greenhouse gases in our atmosphere, that radiation gets absorbed by those molecules and when they absorb it, the IR radiation gets converted to heat. This additional heat stays in the atmosphere, and the net result is that the average global temperature goes up.

Answer 3

Greenhouse gases might reflect sunlight back onto Earth's surface. They also absorb the infrared rays of heat rising from the Earth. Heat rays are also trapped on Earth by the greenhouse gases when it bounces off into the atmosphere, retaining heat on Earth and causing a rise in temperature.

Answer 4

Most of the incoming radiation from the sun is in the form of ultraviolet and visible "long wave" light, which does not warm the greenhouse gases. This radiation warms the surface of the earth. The warm earth emits radiation in the form of "short wave" infrared radiation, which DOES excite the greenhouse gases causing them to warm. When this heat is trapped by the greenhouse gases, then it does not pass easily out to space.

Answer 5

A greenhouse gas is any gas with three atoms. These vibrate and heat up with the warmth rising from the surface of the earth.