So my question which part of the Em spectrum(sun) is responsible for heating of the atmosphere ? Is it visible or infrared or both ?
But, why does infrared contribute more compared to visible ?All parts contribute, infrared more than visible light.
Is there a difference?. I was thinking whether a particular part of em spectrum caused majority of heating.Does the ground count here or are you just wondering about what frequencies of light it absorbs?
You are confusing heat with thermodynamic energy. Heat is energy other than work that is transferred between a system and the environment that surrounds it. Radiative heat transfer is one of the mechanisms by which a system exchanges energy other than work (i.e., heat) with its surrounding environment.It is important to remember that "Heat" and "Infrared" are totally different things. "Heat" is the vibration of molecules. Since there are (almost) no molecules in space, heat cannot travel from the Sun to the Earth directly.
Because the atmosphere is more or less transparent to visible, less so to near infrared. The image below depicts solar radiation at the top of the atmosphere versus that at sea level. The difference between the two is incoming solar radiation that is either absorbed by the atmosphere or reflected back into space by the atmosphere or clouds. Only 19% of the incoming solar radiation is absorbed by the atmosphere; 30% is reflected back into space.But, why does infrared contribute more compared to visible ?
The atmosphere of the earth extends much farther out than the troposphere.The troposphere is heated mainly by the surface of the earth and the temperature decrease with height. Above the tropophere, the ozone in the stratosphere absorbs UV radiation, and temperature increases with height. The mesophere, where temperature decrease with height, has the coldest temperature on the planet where at the top it averages -85C.That is why air at high altitudes is so cold - the photons pass through without heating the air, and the ground is too far away
Sorry algr. I was only trying to comment on that the variation of temperature with elevation is not a direct relation. The upper atmosphere will absorb most of the shorter wavelengths direct from the sun, of which there is not all that much if you look at the graph of the Solar Radiation Spectrum provifded by DH, and the lower atmosphere by ground heating as per the explanation by DH directly below the graph.So the short answer to thorium1010's question is that the ground heats the lower atmosphere, (troposphere) and UV and X-rays heat the parts above the ozone layer?
I think you have that around the wrong wayThe solar spectrum is such that most of the heating by direct absorption of solar photons by atmospheric gases occurs in the UV (oxygen) and in the visible (ozone).
Your numbers don't add up to the solar "constant" of ~1.3kW/m^2.Of the 31 Watts per square meter of ultraviolet radiation that reaches the outside of the Earth's atmosphere from the Sun, only 5 Watts reaches the surface of the Earth. Most of the remaining 26 Watts is scattered by the atmosphere, but a small amount is absorbed--primarily by ozone and oxygen. Of the 154 Watts of visible sunlight at the outside of the atmosphere, 88 Watts reaches the surface. Most of the remaining 66 Watts is absorbed by clouds and particulates and the rest is scattered. Some of this scattered visible light reaches the surface as "skylight". Of the 157 Watts of infrared solar radiation, some 70 Watts reaches the surface. Most of the remaining 87 Watts is absorbed by water vapor and other "greenhouse" gases.
Indeed they do. For historical reasons, heat budgets are usually give in units of W/m^2, averaged over the Earth's entire surface. Since the Earth's surface area is exactly four times its disc area, we divide the Solar Constant of 1,366 joules per square meter per second [Scaffeta & West, 2005] by four. This gives us 342 W/m^2--more or less. That's the number I used for the total incoming solar radiation at the top of the atmosphere. 31 + 154 + 157 = 342Your numbers don't add up to the solar "constant" of ~1.3kW/m^2.