Current Affairs

Issue

Many cities across the country have been adversely affected due to a phenomenon known as ‘urban heat islands’.

 

Background

Urban areas have been more affected in comparison to rural areas due to this weather phenomenon.

 

Details

• Delhi and its surrounding areas witnessed high temperature, reaching almost 50 degree Celsius across different parts.

• In comparison, areas beyond the city limits did not witness such high temperatures. This was a direct result of urban heat island.

 

Urban heat island phenomenon

• It is a phenomenon in which certain pockets within a city witness higher heat load than surrounding or neighbouring areas on the same day.

• These variations can be experienced due to heat remaining trapped within locations that often resemble concrete jungles. Temperatures can vary between 3 to 5 degree Celsius.

 

High temperature in cities

• Rural areas have green cover in the form of plantations, farmlands, forests and trees as compared to urban regions.

• Green areas regulate heat through process known as transpiration, which involves releasing it in the form of water vapour.

• Urban areas do not have enough green cover to regulate heat. As a result, natural temperature regulation is almost absent.

• Cities are made up of materials such as glass, concrete and metals, which are absorbers of heat. Thus, heat remains trapped and form heat islands.

 

Reducing urban heat islands

• Increasing green cover by planting trees in open spaces is the best way to reduce urban heat islands.

• Another way is to use materials and colours that reflect light. Terrace garden have to be developed in all households.

 

Recent observations

• Nighttime temperatures around Delhi and surrounding cities were higher than the nearby rural areas.

• This was attributed to heat island effect. The difference between temperatures was as high as 20 degree Celsius.