Earth Day: The Urban Heat Island Effect-
When summer temperatures rise to uncomfortable levels, you can be guaranteed that being within the limits of a large city does not help anything. In fact, it will be even warmer. This phenomenon of increased temperatures in urban areas is termed the ‘Urban Heat Island Effect’ and it result from urban infrastructure and design.
The ‘concrete jungles’ of our planet are crammed with barren walls, roofs and streets; many of which are dark in colour. By day, concrete and asphalt structures absorb the ultraviolet radiation from the sun and then by night, this radiation is released as thermal infrared radiation which creates a dome of higher temperatures over cities.
Contrastingly, natural landscapes host vegetation and canopies of biomass to create cooler air temperatures due to latent heat; when water changes from a liquid to a gas, energy is needed to overcome the molecular force of attraction between the particles. So, through the process of evaporative cooling, excess heat is utilised by the natural environment.
The influence of the Urban Heat Island effect is profound. In a city with 1 million people or more, the annual mean air temperature can be more than 1–3°C (1.8–5.4°F) warmer than its surroundings. In the evening, the difference can be as high as 12°C (22°F) (USEPA)
For more information, see here: http://www.epa.gov/heatisland/
Image courtesy of http://c3headlines.typepad.com/.a/6a010536b58035970c017744ad1afa970d-pi
Happy Earth Day! May we all work toward preserving this beautiful planet of ours. Regardless of nationality, we all inhabit the same Earth, so we must keep it clean and healthy, since it is the home we all share. So, let us take care of our home, and treat it well, since it’s the only home we have!