What is an urban heat island?
In a city, air temperatures are often as much as 3-4 °C higher than over open country. These higher temperatures are generated by the combustion of fuels in factory, heating, and transport systems, and, more importantly, the release at night of heat which has accumulated during the day in the fabric of the city, for the bricks and concrete of the buildings act as enormous storage heaters. This effect is compounded by air pollution, which reduces night-time terrestrial radiation, and by the low humidity which results from the lack of vegetation. A urban heat island is developed during calm conditions; winds disperse heat.
How does the heat island effect in cities create convection cells?
Monthly rainfall is greater downwind of cities, partially due to the UHI. Increases in heat within urban centers increases the length of growing seasons, and decreases the occurrence of weak tornadoes. The UHI decreases air quality by increasing the production of pollutants such as ozone, and decreases water quality as warmer waters flow into area streams, which stresses their ecosystems. Not all cities have a distinct urban heat island. Mitigation of the urban heat island…
Are urban areas warmer than rural areas?
Urban areas tend to remain warmer that rural areas because of an effect known as 'urban heat island'. This effect of heating is due to the pavement and buildings that are found in urban areas. During the day, the heat radiation from the sun is captured by the pavement and buildings. During the course of the day, and especially in the evening, these 'heat batteries' begin to release that heat, and temperatures can be warmer…
What is the difference between climate and microclimate?
A micro climate is the average temperature in a small area and a climate is the average temperature in a large area. And near bodies of water which may cool the local atmosphere, or in heavy urban areas where brick, concrete, and asphalt absorb the sun's energy, heat up, and re-radiate that heat to the ambient air: the resulting urban heat island is a kind of microclimate.
Is an urban heat island is similar to the Greenhouse Effect or climate change?
No, these are two different things. The urban heat island has to do with how much heat the earth absorbs, while the greenhouse effect is about how much heat the earth loses. During the daytime, sunlight hits the earth. Some of it is reflected back into space, and some is absorbed by the ground. When the ground absorbs sunlight, it heats up. Some of this heat is then transferred to the air by direct contact…
Why are cities usually warmer in the winter than the surrounding countryside?
It is known as The Heat Island Effect or Urban Heat Island. The main cause is the materials that are used to modify the land surfaces (asphalt roads, concrete sidewalks) and buildings contain materials store short wave radiation effectively. A secondary contributor is waste heat generated by energy usage. For more information visit the Related Link.