what causes the greenhouse effect?

Answer 1

If you think about it, the Earth is kind of like a thermos. There is vacuum all around, so most heat that gets into the Earth's system tends to stay there... it has nowhere else to go.

There are just two ways that heat can generally escape: as infrared radiation, or by just not being absorbed in the first place.

Lots of things give off infrared radiation, actually. It's just a kind of light that you can't see, and one of the by-products of heat (if you make things even hotter, they DO start to give off visible light, which is how light bulbs work).

But unless that radiation leaves, it just hits something else and makes that warm too. And there are a number of things that can prevent it from leaving. Methane and carbon dioxide are two very common gases, for example, that do such a good job of preventing infrared from leaving that they are known as 'greenhouse gases'. They are normally produced by the activity of living things, but burning fuels (especially coal and fossil fuels) can make a lot of them too! Even nuclear power can contribute to the greenhouse effect because the huge clouds that churn out of their smokestacks are water vapor which is also a greenhouse gas! In a physical greenhouse, glass does the same thing.

Another major factor in the 'greenhouse effect' is something called 'albedo'. Albedo is just the tendency for incoming light to be deflected off into space without being absorbed and turned into heat. White deserts, clouds, and ice packs have a very high albedo but forests and farmlands typically have a very low albedo. So the more deserts we cultivate and the more we snow packs that melt, the worse our problem gets as we retain more and more heat in the first place. Solar panels also tend to have a fairly low albedo, so covering a desert with them may not be a perfect solution to end global warming from hydrocarbons!

Part of what is disturbing to some scientists is the possibility of a runaway greenhouse effect - the idea that a small increase in temperature can make it easier for a large increase in temperature to occur. You can see how this might be: when it gets warmer, more ice melts and plants grow better, water evaporates more, and when human cities get warmer their citizens tend to use a lot more energy to for air conditioners and the like, which increases fossil fuel use even more. Hopefully, enough people are concerned about this potential that it is never realized!

Answer 2

The effect has to do with the absorbtion spectra of gases. In a way that is simply their color.

Energy from the Sun reaches us as photons (particles of light). Most of the energy is in the visible and near infrared regions. The energy of the photons that a body emits is determined primarily by the body's temperature. The Sun emits relatively high energy photons because it is very hot.

The energy from the Sun keeps the Earth warm. The warm Earth radiates energy to cold outer space. The balance between the energy coming from the Sun and leaving Earth for space determines the temperature on Earth.

Because the Earth is much much cooler than the Sun, the photons that the Earth emits are lower energy photons belonging to the far infrared portion of the spectrum. These are much lower energy than photons from the Sun.

Certain gases are quite transparent to visible and near infrared light but are opaque to far infrared (meaning far infrared cannot pass through them easily). Gases like carbon dioxide, methane, and water vapor are examples.

If the concentration of the far-infrared-opaque gases increases in the atmosphere, the Earth does not radiate as much heat to space. The temperature then rises until the hotter Earth can emit as much energy as it receives from the Sun. When the heat in and out again balance, the temperature stabilizes. As the concentration of greenhouse gases increases, so does the temperature of the Earth.

The term "greenhouse" is appropriate because this is exactly how a greenhouse (or the inside of your car) works. Glass transmits visible and near infrared energy into the greenhouse but blocks the far infrared from leaving making the greenhouse (and you car) hotter than the surroundings when the Sun is out.

Answer 3

The greenhouse effect is caused by the sun's rays coming into our atmosphere, reflecting off earth causing heat, and continuously bouncing back off the ozone layer to earth.

Answer 4

naturally occurring greenhouse gases, or to the enhanced (anthropogenic) greenhouse effect, which results from gases emitted as a result of human activities

Answer 5

haarp technologies used to raise the atmossphere's temperature by 2-3 degrees and have it expand to modify the flow air current upon a very large aera...having the ability to direct the path of an hurricain...but what about florida...??? are they triyng to solve the problem or are they causing it?

Answer 6

Over-active environmentalists.

Answer 7

Burning of fossil fuels (combustion)

Answer 8

global warming