Solar Insolation

I read Steve Goddard's blog, Real Science. He is doing a wonderful job exposing the fraudulent manipulation of the temperature record by the climate alarmist crowd (e.g., NASA).

But lately, he has gotten off-track talking about climate physics. I sent the following comment to one of his posts:

There’s way too much imprecision in this discussion–from all sides.

I used the solar calculator at http://www.esrl.noaa.gov/gmd/grad/solcalc/ to record the sun’s elevation throughout the day. I chose Jun 21, 2014, the summer solstice and recorded the sun’s elevation hourly for three locations: the North Pole, Anchorage Alaska, and a point on the equator.

At the north pole, the sun’s elevation is about 23.5 degrees all day. The sun at Anchorage reaches an elevation of about 52 degrees. The sun at the equator reaches an elevation of 66.6 degrees.

Solar insolation is proportional to the cos(90-elevation angle) for angles above the horizon. Integrating over the 24 hours, I get the following: the north pole sees 9.5 hours direct sun equivalent, Anchorage sees 8.7 hours, and the equator 7.0 hours.

So Steve/Tony is right: at the summer solstice, the Arctic gets more solar insolation than the tropics.

However, this statement is misleading in many ways. I’ve neglected the effect of the lower sun’s rays at the pole being absorbed more by the atmosphere than at the equator. The peak solar elevation is much higher at the equator than the pole.

Furthermore, the summer solstice is the most favorable day of the year for the north pole. That’s the day it gets most solar insolation and the day the equator gets least (though the equator doesn’t vary much). (BTW, the south pole gets no insolation that day.)

Finally, a day’s solar insolation affects that location’s change in temperature far more than it affects it’s absolute temperature. The tropics are warm all year around, but the pole is very cold coming out of winter.

Blaming the cold weather at the poles on the lack of greenhouse gases is wrong. (BTW, the standard assumption is that CO2 is distributed uniformly.) The poles are cold because they get less sunlight over the year.

Water is immensely important to the planet’s temperature distribution. The oceans transfer heat from the tropics poleward, clouds and thunderstorms cool the tropics, and clouds help retain heat at night. The atmosphere also contributes with convection and winds. It’s complicated and oversimplifying is misleading at best.