I call this one the Energy Cycle, but it really boils down to the heat from our star’s energy output (no pun intended—actually it was intended, I just thought I’d say that). Raise your hand if you know how many Watts of energy the sun emits. Okay, great, you can put your hands down now. For those of you who don’t know, let me tell you. 

The total amount of energy leaving the sun’s surface is approximately 63.3 Million Watts per square meter. But by the time the sun’s energy has spread out and traveled 93 million miles to reach the earth’s outer atmosphere, it is reduced to an average of 1367 Watts per square meter, which is called the Solar Constant.

The earth actually receives between 1353 and 1395 Watts per square meter. The amount of energy received is dependent on the sun’s varying energy output and the varying distance between the sun and the earth as the earth orbits the sun. So the Solar Constant is really a variable constant. (That is an oxymoron for all you liberals who believe in truth, justice and the American way.)

You might think that is a bunch of Watts and that the earth should burn up if it receiving that much energy. You would be absolutely right except for one thing. The earth has an atmosphere, made up of Nitrogen, Oxygen, Argon, Carbon Dioxide, Methane, Hydrogen, Helium, and the lesser irregular gases expelled by buffoons who ‘believe’ that man causes global warming. All these gases are essential with the exception of one. I’ll let you guess which one. Another thing that certain pseudo-scientists can’t account for in their computer models are clouds. Again for you liberals, those are those white fluffy things that move around in the sky, those things you have your head in most of the time. All these things reflect or absorb and re-emit back into space. Energy is also reflected off of the snow and ice in our mountains and at the poles.

Another thing that alters the amount of the Solar Energy reaching the earth’s surface is the angle of incidence. Since the earth is round the solar energy reaches a point on the earth at an angle that depends on the season and the latitude. Water only reflects 5% of the solar energy that hits it at an angle that is near normal - like at the equator, in the Gulf of Mexico. But water reflects upwards to 15% if the incident angle is larger than 60 degrees. That means that water in the North Atlantic and near the poles reflects a significant amount of energy back into space.

So, if we do the math, we find that the sun’s energy is reduced from 63.3 Million Watts per square meter to only 475 Watts per square meter by the time it strikes your front yard. Taking the 475 Watts per square meter, assuming 12 hours of sunshine, calculates to 5,678 Watt-hours per square meter per day. That means that on the average, every square meter of the earth’s surface receives enough energy in 12 hours to light one 60 Watt incandescent light bulb for 4 days. The solar energy hitting your 50 X 110 ft. lot in one day would power 29,000 100-miniature-light-strands for 4 hours! Talk about Christmas spirit!

You might say, "WOW, that’s a lot of energy that still strikes the earth, and that it still seems like the earth should be scorched." But here are some facts that you must consider: much of the energy is absorbed by moisture in the air and in the clouds. One fourth of the solar energy that strikes the oceans, lakes, and dew is used to evaporate the Dihydrogen Monoxide. Some of the energy powers the wind and waves; some is used by vegetation for photosynthesis. Most of the sun’s energy does reach the earth’s surface, heating oceans, land, roads, parking lots, your SUV’s dashboard (hot!), buildings, rooftops, and you guessed it—us. Then that heat is transmitted back into the atmosphere via convection, conduction, evaporation, and back into space via infrared radiation.

Trade winds and convection currents (columns of rising hot air, also known as thermals and not to be confused with bloated politicians) are always moving across the earth pulling heat energy from the surface. As these air currents mix and rise they disperse the heat energy that eventually escapes into space as radiant energy. Moisture near the surface evaporates and the water vapor is carried upward by the same air currents. As the water vapor cools, it condenses as rain, snow, or clouds. Heat is released, and again it makes its way into the upper atmosphere, and eventually into space as radiant energy. This energy cycle has been occurring since the earth’s beginning.

The earth-to-space heat exchange rate is dependent several thing including convection currents, wind velocity, and the concentration of ‘greenhouse’ gases, especially water vapor (H20). Light wind, slow convection currents, and high humidity cause the heat transfer process to slow and local air temperatures to increase, but it never stops and it is never trapped. On a humid day in Houston, when the air is saturated with hot, evaporated moisture, you pray for a cool breeze to whisk away some of the unbearable heat. After the sun sets, the nights are muggy because moisture in the air holds heat close to the earth’s surface and not because there is an extra molecule of CO2 in the air.

Here is an interesting fact that you might want to know: Water vapor has 24% more heat capacity than dry air, and dry air has 7% more heat capacity than CO2. Heat capacity is the measure of a substance’s ability to retain heat. Adding more water vapor (higher humidity) increases the air’s ability to retain heat, while adding more CO2 reduces air’s ability to retain heat. When is the last time you heard that on the evening news?

Through convection, conduction, evaporation, and minute amounts of infrared radiation released from the surface the energy cycle of the earth is balanced, such that, for all of geological history, the average global temperature has not varied by more than 16° Celsius. And most of the temperature swing has been below the current average global temperature (think Ice Ages). But in the last 10,000 years, the average global temperature has only varied by 3.3° Celsius and the temperature has mostly been above the current average global temperature, as much as 1.3° Celsius higher than today. For the last ten millennia, the average global temperature has been falling!

Thems the facts, my dear friends.