What is greenhouse effect?

Answer 1

The Earth receives energy from the Sun in the form of radiation. The Earth reflects about 30% of the incoming solar radiation. The remaining 70% is absorbed, warming the land, atmosphere and oceans.

To the extent that the Earth is in a steady state, the energy stored in the atmosphere and ocean does not change in time, so energy equal to the absorbed solar radiation must be radiated back to space. Earth radiates energy into space in the infrared wavelengths with an intensity that increases with increasing temperature. Therefore, one can think of the Earth's temperature as being determined by the infrared flux needed to balance the absorbed solar flux.

The visible solar radiation heats the surface, not the atmosphere, whereas most of the infrared radiation escaping to space is emitted from the upper atmosphere, not the surface. The infrared photons emitted by the surface are mostly absorbed by the atmosphere and do not escape directly to space.

The reason this warms the surface is most easily understood by starting with a simplified model of a purely radiative greenhouse effect that ignores energy transfer in the atmosphere by convection (sensible heat transport) and by the evaporation and condensation of water vapor (latent heat transport). In this purely radiative case, one can think of the atmosphere as emitting infrared radiation both upwards and downwards. The upward infrared flux emitted by the surface must balance not only the absorbed solar flux but also this downward infrared flux emitted by the atmosphere. The surface temperature will rise until it generates thermal radiation equivalent to the sum of the incoming solar and infrared radiation.

A more realistic picture taking into account the convective and latent heat fluxes is somewhat more complex. But the following simple model captures the essence. The starting point is to note that the opacity of the atmosphere to infrared radiation determines the height in the atmosphere from which most of the photons emitted to space are emitted. If the atmosphere is more opaque, the typical photon escaping to space will be emitted from higher in the atmosphere, because one then has to go to higher altitudes to see out to space in the infrared. Since the emission of infrared radiation is a function of temperature, it is the temperature of the atmosphere at this emission level that is effectively determined by the requirement that the emitted flux balance the absorbed solar flux.

But the temperature of the atmosphere generally decreases with height above the surface, at a rate of roughly 6.5 °C per kilometer on average, until one reaches the stratosphere 10-15 km above the surface. (Most infrared photons escaping to space are emitted by the troposphere, the region bounded by the surface and the stratosphere, so we can ignore the stratosphere in this simple picture.) A very simple model, but one that proves to be remarkably useful, involves the assumption that this temperature profile is simply fixed, by the non-radiative energy fluxes. Given the temperature at the emission level of the infrared flux escaping to space, one then computes the surface temperature by increasing temperature at the rate of 6.5 °C per kilometer, the environmental lapse rate, until one reaches the surface. The more opaque the atmosphere, and the higher the emission level of the escaping infrared radiation, the warmer the surface, since one then needs to follow this lapse rate over a larger distance in the vertical. While less intuitive than the purely radiative greenhouse effect, this less familiar radiative-convective picture is the starting point for most discussions of the greenhouse effect in the climate modeling literature.

The term "greenhouse effect" is a source of confusion in that actual greenhouses do not warm by this same mechanism........

Answer 2

The greenhouse effect, discovered by Joseph Fourier in 1829 and first investigated quantitatively by Svante Arrhenius in 1896, is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface. The name comes from an analogy with the warming of air inside a greenhouse compared to the air outside the greenhouse. The Earth's average surface temperature is about 20-30°C warmer than it would be without the greenhouse effect . In addition to the Earth, Mars and especially Venus have greenhouse effects.

Answer 3

Earth's atmosphere acts like a greenhouse, warming our planet in much the same way that an ordinary greenhouse warms the air inside its glass walls. Like glass, the gases in the atmosphere let in light yet prevent heat from escaping. This natural warming of the planet is called the greenhouse effect.

Greenhouse gases -- carbon dioxide, methane, nitrous oxide, and others -- are transparent to certain wavelengths of the Sun's radiant energy, allowing them to penetrate deep into the atmosphere or all the way to Earth's surface. Clouds, ice caps, and particles in the air reflect about 30 percent of this radiation, but oceans and land masses absorb the rest, then release it back toward space as infrared radiation. The greenhouse gases and clouds effectively prevent some of the infrared radiation from escaping; they trap the heat near Earth's surface where it warms the lower atmosphere. If this natural barrier of atmospheric gases were not present, the heat would escape into space, and Earth's mean global temperatures could be as much as 33 degrees Celsius cooler [about -18 degrees Celsius as opposed to 15 degrees Celsius].

The greenhouse effect is important to life on Earth, without it the Earth would be far too cold for us. But some scientists are concerned that humans are producing too many greenhouse gases, and that we may be warming the Earth too much. The first step to a safe future is to be aware of the possible problems. Next we must study climate and atmospheric trends, which will take many years of observation. NASA is very involved in these studies, measuring greenhouse gases in the atmosphere from satellites in space. As we develop a deeper understanding of climate trends, we can better predict what affects we have on our environment, and how to ensure a healthy future.

Click for image http://www.virtualsciencefair.org/2005/stro5c0/public_html/greenhouse_effect.jpg

Answer 4

There are some gases which absorb the IR radiation of the sun.Among them the most important are carbon-di-oxide,water vapour methane and ozone.These are called ' greenhouse gases'.The incoming solar radiation is a short wave radiation that is not directly obsorbed by the amosphere .But it heats the earth's surface first and is reflected by the earth as long wave radiation which in turn heats the atmosphere above it by conduction. Among the above gases,water vapour is a powerful obsorber of the heat radiation that is emitted by the earth,s surface.It is because of this property of water vapour that the atmosphere near the earth's surface does not cool rapidly when there is a layer of low or medium cloud cover.The heat radiation from the earth's surface is readily absorbed by the cloud cover(which contains the water vapour as water droplets) and re-radiates back to the earth's surface with the result there is less cooling of the surface and the atmosphere near the surface becomes warm and sultry.This effect of water vapour and the cloud layer is called the 'grenhouse effect'.Even though the other gases mentioned above are also contributing to this effect,water vapour and carbon-di- oxide are the major contributors.

Answer 5

Anything which allows heat to enter but not escape, thereby raising the temperature; like the glass panes in a greenhouse. In current trendy environmental circles, it's a theory that certain gasses in the atmosphere will allow solar radiation in, but prevent infrared from escaping at night, causing the planet to warm up-- "global warming".
(WARNING: BEGINNING SATIRE!) This will result in long, dull lectures by Al Gore and after all that hot air makes the ice caps melt, we'll have to live on a boat with Kevin Costner.
Someone must stop this horror!

Answer 6

Have u ever travelled in a bus on a hot summer mid day with the glass windows closed and sun light peeping in? The infra red (heat) radiation from with in the bus can not escape as th glass is opaque for IR radiation. U will certainly feel hot. The same thing happens when the heat radiation from the surface of the earth fails to escape because of some gases which absorb IR radiation. CO2,methane,ozone and water vapour are important green house gases. They absorb heat radiation reflected from the surface of the earth and prevent them from radiating in to outer space. So, the earth becomes warm. The average temperature increases.

Answer 7

The Greenhouse effect is what happens when there are TOO MANY greenhouse gases. Greenhouse gases are good, keeping us warm, but too many of 'em can cause global warming, which is the warming of the earth. It has caused many dangers, such as THE NORTH POLE IS MELTING!!

What will happen to polar bears? AND HOW AM I GOING TO GET PRESENTS FOR CHRISTMAS IF SANTA IS DROWNED?

Answer 8

The greenhouse effect, discovered by Joseph Fourier in 1829 and first investigated quantitatively by Svante Arrhenius in 1896, is the process in which the emission of infrared radiation by the atmosphere warms a planet's surface. The name comes from an analogy with the warming of air inside a greenhouse compared to the air outside the greenhouse. The Earth's average surface temperature is about 20-30°C warmer than it would be without the greenhouse effect. In addition to the Earth, Mars and especially Venus have greenhouse effects.
The Earth receives energy from the Sun in the form of radiation. The Earth reflects about 30% of the incoming solar radiation. The remaining 70% is absorbed, warming the land, atmosphere and oceans.

To the extent that the Earth is in a steady state, the energy stored in the atmosphere and ocean does not change in time, so energy equal to the absorbed solar radiation must be radiated back to space. Earth radiates energy into space in the infrared wavelengths with an intensity that increases with increasing temperature. Therefore, one can think of the Earth's temperature as being determined by the infrared flux needed to balance the absorbed solar flux.

The visible solar radiation heats the surface, not the atmosphere, whereas most of the infrared radiation escaping to space is emitted from the upper atmosphere, not the surface. The infrared photons emitted by the surface are mostly absorbed by the atmosphere and do not escape directly to space.

The reason this warms the surface is most easily understood by starting with a simplified model of a purely radiative greenhouse effect that ignores energy transfer in the atmosphere by convection (sensible heat transport) and by the evaporation and condensation of water vapor (latent heat transport). In this purely radiative case, one can think of the atmosphere as emitting infrared radiation both upwards and downwards. The upward infrared flux emitted by the surface must balance not only the absorbed solar flux but also this downward infrared flux emitted by the atmosphere. The surface temperature will rise until it generates thermal radiation equivalent to the sum of the incoming solar and infrared radiation.

A more realistic picture taking into account the convective and latent heat fluxes is somewhat more complex. But the following simple model captures the essence. The starting point is to note that the opacity of the atmosphere to infrared radiation determines the height in the atmosphere from which most of the photons emitted to space are emitted. If the atmosphere is more opaque, the typical photon escaping to space will be emitted from higher in the atmosphere, because one then has to go to higher altitudes to see out to space in the infrared. Since the emission of infrared radiation is a function of temperature, it is the temperature of the atmosphere at this emission level that is effectively determined by the requirement that the emitted flux balance the absorbed solar flux.

But the temperature of the atmosphere generally decreases with height above the surface, at a rate of roughly 6.5 °C per kilometer on average, until one reaches the stratosphere 10-15 km above the surface. (Most infrared photons escaping to space are emitted by the troposphere, the region bounded by the surface and the stratosphere, so we can ignore the stratosphere in this simple picture.) A very simple model, but one that proves to be remarkably useful, involves the assumption that this temperature profile is simply fixed, by the non-radiative energy fluxes. Given the temperature at the emission level of the infrared flux escaping to space, one then computes the surface temperature by increasing temperature at the rate of 6.5 °C per kilometer, the environmental lapse rate, until one reaches the surface. The more opaque the atmosphere, and the higher the emission level of the escaping infrared radiation, the warmer the surface, since one then needs to follow this lapse rate over a larger distance in the vertical. While less intuitive than the purely radiative greenhouse effect, this less familiar radiative-convective picture is the starting point for most discussions of the greenhouse effect in the climate modeling literature.

The term "greenhouse effect" is a source of confusion in that actual greenhouses do not warm by this same mechanism

Answer 9

Phenomenon in which earth's atmosphere traps the heat frm the sun &prevents it from reradiating back into the outer space.
Sun emits radiation in diferent wavelengths.Most of the harmful radiations are absorbed by the ozone layer.Light in the visible region passes through the ozone layer & falls the earth thereby the earth gets heated up.In the normal course,the temp. of earth is balanced by reflecting back the absorbed energy to the outer space, mainly in the form of IR radiations.
But due to presence of excess amount of gases like CO2,CH4 etc in the atmosphere ,the heat radiated by the earth's surface can't pass freely into the outer space.This result in an abnormal increase in temp. of earth's surface,called green house effect.

Answer 10

EP, permit me verify from the outset that i be conscious of little or no in this concern, so, inspite of our disagreements interior the previous, I’m *not* contradicting you right here – in basic terms attempting to understand. I’m additionally at a loss for words by using the section you highlighted. If the planet gained 240 W/m^2 of potential from the sunlight, how can the ambience “radiate 240 W/m^2 into area, [and] additionally radiate 240 W/m^2 lower back in the direction of the floor”? The regulation of conservation of potential states that potential can't be created or destroyed, yet, in accordance on your description, the ambience is receiving 240 W/m^2, yet reradiating a entire of 480 W/m^2. in the start look this seems to be like impossible. What am I lacking that makes this artwork? :::EDIT::: Oh, so the “radiate 240 W/m^2 into area, [and] additionally radiate 240 W/m^2 lower back in the direction of the floor” quote is the region *after* equilibrium is reached? So it’s the situation on the top ingredient, not the commencing ingredient?