Does one have to deny that the so-called green house gases (GHG)s have an effect on global temperatures to be a skeptic? Many of the big-league skeptics believe that the GHGs do play a part in global temperature. So maybe not.
The following is a quote from Climate Change Reconsidered II** :
“ As carbon dioxide concentrations increase so too does the intensity of back radiation at the surface across the active wavebands of CO2, and because this radiation emanates from a lower and warmer layer of the atmosphere, the magnitude of the back radiation increases. Consequently, the net infrared radiation emanating from the surface is reduced, causing a rise in temperature that generates increased heat exchange and evaporation. This surface warming also contributes to an increase in convective instability”.
So, hold on and let me explain why I believe this.
First, a look at the big picture. The Sun’s surface is somewhere about 5500 C. Radiation goes out in all directions with some of it directed toward Earth. This is Earth’s principal source of energy. This radiation travels 93 million miles in about 8 minutes to reach Earth. It loses much of its strength in the journey, but at the top of our atmosphere, its strength is nominally 1365 watts per square meter. The Sun’s radiation mainly consists of photons of visible light, ultraviolet and infrared. The full force of the Sun’s radiation seldom reaches the Earth surface because of clouds, reflection off snow and ice, scattering in the atmosphere for example and the angle that the Sun’s rays strike the surface. Further complicating this topic is the fact on average, the Sun only shines on any place on Earth for more than 12 hours per day.
Many charts showing the Earth’s average energy budget use 340 w/m² because when you factor in the length of the day and the spherical geometry of the Earth the effect is about ¼ the energy at the top of the atmosphere at noon. While the Energy budget charts are useful, I believe they get in the way of understanding the GHG effect. So, the following will uses actual measured radiation data and not the hypothetical 340w/m².
To get an idea of what happens at the surface, lets take a look at the data collected by the Surface Radiation Project. The Surface Radiation Budget Network (SURFRAD) was established in 1993 through the support of NOAA’s Office of Global Programs. The SURFRAD mission is clear:
“its primary objective is to support climate research with accurate, continuous, long-term measurements of the surface radiation budget over the United States”.
SURFRAD currently has 7 operating stations. These stations are very well equipped. They can measure upwelling and downwelling solar, upwelling and downwelling IR, temperature, RH, wind speed, cloud cover, UVb and several others. The SURFRAD website allows you to make charts of the collected day. For starters I have plotted some data from the Desert Rock, Nevada SURFRAD site.