Impact of human activities on urban heat climate

George C By George C, 30th Apr 2015 | Follow this author | RSS Feed | Short URL http://nut.bz/437kr71o/
Posted in Wikinut>Guides>Nature>Weather

The impact of manmade structures and a wide variety of combustion sources on city temperatures creates heat island zones. Cities have become hotspots for higher temperatures in a way that affects neighboring areas lying as far as thousands of miles.

Impact of human activities on urban heat climate

The impact of manmade structures and a wide variety of combustion sources on city temperatures creates heat island zones. Cities have become hotspots for higher temperatures in a way that affects neighboring areas lying as far as thousands of miles. Scientists have conducted a number of studies aimed at uncovering the extent of this phenomenon. Many reports indicate that human activities generate sufficient heat to transform the nature of jet streams as well as other atmospheric elements. Luke Howard first mentioned the urban heat island in the early 1810s.

A study in climate change revealed that the phenomenon affects neighboring areas in a dissimilar fashion, some experience an increase in temperature while others cool down. Excess heat generated in cities located in the Northern Hemisphere triggers a rise in temperature in winter across northern parts of America and Asia. According to scientists at the Scripps Institution of Oceanography; University of California, San Diego; Florida State University; and the National Center for Atmospheric Research, the net impact on global mean temperatures is almost insignificant.

Trends

The average increase is determined by the amount of heat moved by atmospheric and oceanic circulations, which hovers around 0.3 percent. The movement occurs on higher altitudes. Some scientists argue that the urban heat island effect is closely linked to global warming in comparison to greenhouse gases. This is despite research results showing minimal impact on global mean temperatures. The atmospheric changes are more apparent at night than during daytime; wind speed also plays a crucial role in this regard.

Raw materials

Some raw materials used in the construction of many manmade structures retain a significant amount of heat. This in turn contributes to the urban heat island effect. Engineers have suggested the use of white paint on roofs and other surfaces. However, computer-modeling systems employed by Mark Jacobson of Stanford University in California, showed that despite the cooling benefits of white paint, it still compounded the global warming problem due to reduced cloudiness.

White roofs

Jacobson revealed that the reduction occurs owing to the amplification of air stability, thus lowering the vertical movement of energy and moisture towards the clouds. The decrease in cloudiness translates to increased surface exposure to sunlight. White roofs reflect more sunlight to the atmosphere, which raises levels of light absorption by dark pollutants. Whenever elements, such as black carbon soak up light this leads to higher atmospheric temperature.

A report by published by the National Center for Atmospheric Research indicates that white roofs offer substantial benefits in terms of reduction in electricity use in summer. The center argues that white roofs translate to minimal air conditioning, which in turn offsets heavy electricity use in winter.

Use of photovoltaic panels

Some sections of the scientific community contend that the best option involves the installation of photovoltaic panels on roofs. The panels play a crucial role in reducing fossil fuel emissions by lowering electricity demand in addition to cutting down sunlight absorption by manmade structures. Photovoltaic panels on roofs have the capacity to convert sunlight to electricity. They do not contribute to the absorption of light by airborne pollutants because light is not reflected into the atmosphere, which exacerbates the urban heat island effect.

Tags

Climate, Humans, Urban Heat

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