Thursday, March 1, 2018

Junk Science and climate change

It is a foregone conclusion of the author that the only variable is "global climate change."

Urban Heat Islands

From Wikipedia:


How much heat?
A lot!

Most people can visualize the size of a two car garage.  They have roofs that  typically measure 25' by 25'.

Washington DC averages 3.6 inches of rain each month May-through-August, inclusive.  That means that 187 cubic feet of water falls on that 25' by 25' patch each month.  If paved, that water runs into a storm drain rather than being available for trees and grass to transpire.

That rain lost to run-off denies that 25' by 25' footprint of 11 million BTUs of heat sink due to transpiration for each month of the summer.  11 million BTUs is the equivalent of burning one hundred gallons of gasoline.  Every month of the summer.  For each 25' by 25' patch of pavement in the DC metro area.

(The math: The latent heat of evaporation for water is 970 BTU/lb X 64 pounds per cubic foot for 62K BTU per foot of water.  62K * 187 ft^3 = 11.6 million BTU.  A gallon of gas has 114,000 BTU per gallon.  1.16e+6/1.14e+4= about 1e2 or one hundred.)

Another factor involves convective heat transfer.  Sunlight that is converted to heat in the top of a tree's canopy is not heating up the air at ground level.  The wind velocity is higher 40' above ground and there is more mixing and churning as the wind whistles through the tree tops.  The temperature rise impacts a much deeper blanket of air than the heat coming off a blacktopped parking lot and consequently the maximum air temperature is much lower.


  1. The reporterette has likely never heard of such stuff

    reflecting heat source.

  2. Good point on the evaporation. I didn't know that.
