"The City of Chicago has produced a map of urban
hotspots to use as a planning tool to target areas that could most benefit
from heat-island reduction initiatives such as
reflective or green roofing, and tree planting.
Created using satellite images of daytime
and nighttime temperatures, the map
shows the hottest 10 percent of both day
and night temperatures in red, and the
hottest 10 percent of either day or night
The City is working to reduce urban
heat buildup and the need for air
conditioning by using reflective roofing materials. This thermal
image shows that the radiating temperature of the City Hall’s
“green roof” – covered with soil and vegetation – is up to 77°F
cooler than the nearby conventional roofs.411
Global Climate Change Impacts in the United States, Thomas R. Karl, Jerry M. Melillo, and Thomas C. Peterson,
(eds.). Cambridge University Press, 2009. p. 118
I looked at reference 411. It said this.
411 Several different city of Chicago analyses have substantiated the
finding of up to 77 degree difference – for example, see City of
Chicago, Department of Environment, Undated: City Hall Rooftop
Garden. [Web site]
Being curious, with an ability to connect things, I immediately thought of Baltimore, Maryland's temperature station on a rooftop.
Yes, the incompetent weather service does indeed measure the temperature in places that might be, oh, maybe, 77 deg F too hot!. Being above the rocks it is most certainly less than that but it will still be far too hot. Yet this USHCN station is supposed to be one of the better stations for use in global warming studies. Yeah right.
Keeping that in mind, I dug around the Chicago web site and found this.
"On August 9, 2001, at 1:45 pm, when the temperature was in the 90's, the following measurements were obtained:
City Hall Roof (paved) 126 - 130°F
City Hall Roof (planted) 91 - 119°F
County Roof (black tar) 169°F
That's at least a 50°F difference between the garden roof and a black roof!
I found a graph showing the daily temperature
Note the 113.4 deg F temperature. I tried to look up Chicago's temperature on Aug 8, 2001 but it isn't in the USHCN. So, I looked at Aurora Illinois, just a few miles away. Its maximum temperature was 96 F on that day. Reuters says that the Chicago temperature 'flirted' with 100, meaning it wasn't 100, yet, the roof top temperature was above 100 F, it was 13 deg hotter than 100!
From Anthony Watts' site here is Santa Ana, CA's thermometer, on the roof top as well. Of course, the usual apologetical excuses will be given the by the AGW crowd, that this doesn't really matter--nothing ever does to true believers.
Surely the 7.5 deg rise in temperature in Santa Ana California has nothing what so ever to do with the thermometer on a hot tin roof--that doesn't matter, does it AGW ideologues?