The moon has no atmosphere but the same amount of solar input as the Earth. its surface is much colder when in darkness and much warmer when in the light but the average temperature is lower than the average temperature on earth. the dark parts quickly radiate away any energy retained by thermal inertia and are then warmed only by heat produced by fission in the core. the warm parts in the light radiate away energy at a tremendous rate because radiation emitted is proportional to the temperature (in Kelvin) to the fourth power.
the earth does have an atmosphere. sunlight hitting the surface not only warms the surface but passes some of that energy to the atmosphere by conduction. during daylight warming the air molecules not only warm (kinetic energy) but puff up (potential energy). during nighttime cooling energy stored as both kinetic and potential is released, but in all directions, so that some of the energy returns to the surface. this energy does not 'warm' the surface directly because the surface is warmer than the atmosphere, therefore the net radiation energy transfer is always outward through the atmosphere and into space. to give a made up example if the earth surface was radiating 100w but getting 10w back from atmospheric radiation then the net loss would be 90w. the surface would still be cooling but at a slower rate.
next, add greenhouse gases. the surface radiation no longer directly escapes to space. while conduction is still taking place, part of surface radiation is absorbed into the atmosphere and is converted through molecular collisions into kinetic and potential energy. the atmosphere is now both warmer and higher. for example, if half of the surface radiation is captured by the atmosphere by GHGs, and half of that is returned to the surface, then the surface is getting back the 10w from conduction and radiation plus half of the 50w absorbed, 25w. the surface is losing 100w but getting back 10w and 25w for a net loss of only 65w.
obviously this lower rate of loss would affect the surface temperature. in the first case, atmosphere only, the solar input would collect at the surface until the temperature rose enough that the total surface radiation made up for the 10w imbalance of energy being released into space. in the GHG example the surface would warm even more to make up for the 35w deficit of outgoing radiation.
this is an absurdly simplified explanation. in real life we know that the energy received from the Sun must exactly match the outgoing energy leaving into space or there will be cooling or warming. we know how much Solar input the surface receives (less than 200w on average) and we know how warm the surface is (~15C, 400w). the only way we can close that energy budget is by back radiation returning to the surface from the atmosphere.
we also know, by measurement, that the type and amount of radiation released from the surface does not come out from the other side of the atmosphere. where did the energy go, if not into the total energy of the atmosphere?
I am supporting the Greenhouse Effect here. I do not support the warmer's version of feedbacks etc. But that is another story with its own complications. For now I just want people to think thing through and come to the inescapable conclusion that there is a Greenhouse Effect. And while I dont agree with IPCC consensus projections for increased CO2, there must be a warming influence of undetermined quantity for increased GHGs.
the earth does have an atmosphere. sunlight hitting the surface not only warms the surface but passes some of that energy to the atmosphere by conduction. during daylight warming the air molecules not only warm (kinetic energy) but puff up (potential energy). during nighttime cooling energy stored as both kinetic and potential is released, but in all directions, so that some of the energy returns to the surface. this energy does not 'warm' the surface directly because the surface is warmer than the atmosphere, therefore the net radiation energy transfer is always outward through the atmosphere and into space. to give a made up example if the earth surface was radiating 100w but getting 10w back from atmospheric radiation then the net loss would be 90w. the surface would still be cooling but at a slower rate.
next, add greenhouse gases. the surface radiation no longer directly escapes to space. while conduction is still taking place, part of surface radiation is absorbed into the atmosphere and is converted through molecular collisions into kinetic and potential energy. the atmosphere is now both warmer and higher. for example, if half of the surface radiation is captured by the atmosphere by GHGs, and half of that is returned to the surface, then the surface is getting back the 10w from conduction and radiation plus half of the 50w absorbed, 25w. the surface is losing 100w but getting back 10w and 25w for a net loss of only 65w.
obviously this lower rate of loss would affect the surface temperature. in the first case, atmosphere only, the solar input would collect at the surface until the temperature rose enough that the total surface radiation made up for the 10w imbalance of energy being released into space. in the GHG example the surface would warm even more to make up for the 35w deficit of outgoing radiation.
this is an absurdly simplified explanation. in real life we know that the energy received from the Sun must exactly match the outgoing energy leaving into space or there will be cooling or warming. we know how much Solar input the surface receives (less than 200w on average) and we know how warm the surface is (~15C, 400w). the only way we can close that energy budget is by back radiation returning to the surface from the atmosphere.
we also know, by measurement, that the type and amount of radiation released from the surface does not come out from the other side of the atmosphere. where did the energy go, if not into the total energy of the atmosphere?
I am supporting the Greenhouse Effect here. I do not support the warmer's version of feedbacks etc. But that is another story with its own complications. For now I just want people to think thing through and come to the inescapable conclusion that there is a Greenhouse Effect. And while I dont agree with IPCC consensus projections for increased CO2, there must be a warming influence of undetermined quantity for increased GHGs.