Image caption: On May 11-12, 1997, NASA used a specially outfitted Lear Jet to collect thermal data on metropolitan Atlanta, Georgia. Nicknamed "Hot-Lanta" by some of its residents, the city saw daytime air temperatures of only about 26.7 degrees Celsius (80 degrees Fahrenheit) on those days, but some of its surface temperatures soared to 47.8 degrees Celsius (118 degrees Fahrenheit). In this image, blue shows cool temperatures and red shows warm temperatures. Pockets of especially hot temperatures appear in white. (Image courtesy NASA/Goddard Space Flight Center Scientific Visualization Studio.) via Wikipedia
Is it hot in here or is it just the megacity a continent away? Just when you thought that climate change couldn't get any more controversial, a new study reveals that urban heat island can affect the weather thousands of miles away:
As a result of the urban heat island, the temperature over a wide area can rise or fall by a couple of degrees. Read more over at the Smithsonian Magazine's Suprising Science Blog: Link
“What we found is that energy use from multiple urban areas collectively can warm the atmosphere remotely, thousands of miles away from the energy consumption regions,” said lead author Guang Zhang of the Scripps Institute of Oceanography. “This is accomplished through atmospheric circulation change.”
In studying the excess heat generated by daily activities in cities around the Northern Hemisphere, Zhang and colleagues from the National Center for Atmospheric Research and elsewhere found that a significant amount of the heat is lifted into the jet stream, causing the fast-moving current of air to widen. Overall, this causes an average of 1.8 degrees Fahrenheit warming during the winter for most of North America and Asia, and 1.8 degrees Fahrenheit cooling during the fall for Europe.
The explanation for this phenomenon is fairly simple: A disproportionate amount of the excess heat produced by human activity is concentrated in a few key areas, and many of these areas (the East and West coasts of the U.S., as well as Western Europe and East Asia) lie underneath the jet stream and other prominent air circulation belts. When the heat is taken up into the system, it disrupts the normal flow of energy and can cause surface temperatures to change in distant locales affected by the same air circulation patterns.