Urban Heat Island effect: defination, causes and solution

urban heat island dome
Source: climatekids.nasa.gov

In this article, we will be discussing Urban Heat Island Effect (UHI effect) with its definition, causes, impacts, and of course solutions.

As you can understand by its name heat island, the island of heat. Hence, the name suggests that it has more heat than the surrounding.

Urban Heat Island Definition

You must have experienced that cities or urban areas are much warmer than their surrounding or rural areas. This phenomenon of urban areas is known as the urban heat island effect.

In other words, the UHI effect occurs when the average temperature of urban areas increases.

Urban heat island effect temperature difference

The average temperature difference can be 1 to 3-degree celsius. However, on a calm and clear night, it can be as much as 12-degree celsius.

Various causes of urban heat island effect

The main factors are anthropogenic modifications that we do for our survival. In other words, this is the problem of urbanization.

Urbanization leads to deforestation, new infrastructure, Industries, etc.

First, deforestation as a factor

For the development of new infrastructure, deforestation takes place. and, the number of trees decreases drastically.

Why trees are so important? Trees and plants make their food by photosynthesis. During photosynthesis, they convert groundwater into vapor through their leaves. We call it transpiration.

Transpiration acts as nature’s air conditioner.


Therefore, the decrease in the number of trees will lead to less transpiration, intern leads to an increase in temperature. but, this does not happen in rural areas because they have enough trees and plants.

Second, Infrastructure development

The material used in buildings, roads, rooftops, etc. such as bricks, asphalt, concrete does not transmit light. The thermal conductivity of these materials is very high. Therefore, they absorb more heat than the surrounding suburbs or rural areas.

Furthermore, the skyscraper-like buildings in urban areas increase the surface areas for solar radiation. This is not the case in rural surroundings.

Third, Industries and transportation

Pollution is also one of the major causes of the urban heat island effect. The smoke from Industries and vehicles contribute a major part to air pollution.

This pollution in urban areas creates the Urban heat island dome. The UHI dome traps the albedo (reflected part of solar insolation) in it which increases the temperature.

What are the impacts of the UHI effect?

  • It decreases the air quality in cities.
  • Due to the increase in temperature, there is an increase in species that like warm temperatures such as lizard, geckos, etc. Insects such as ants are more in urban areas than in rural areas.
  • Cities tend to experience heatwaves which causes the health of animals and humans. Therefore, leading to heat cramps, sleep deprivation, and increased mortality rates.
  • UHI effect also impacts the nearby water bodies and water species.

Urban heat island solution/ Way forward

We have discussed the causes of UHI. So, we can derive the solutions from the factors causing it. The following can be –

  • Planting as much as trees and plants as possible on rooftops, along roads, etc. This will increase the transpiration and, also, will absorb less heat than the bear surface.
  • Painting surfaces with light color. This will decrease heat absorption.
  • Painting the rooftop with green color and also, implementing solar panels on the rooftop.
  • Using limestone aggregate along with asphalt making the roads greyish and pinkish.

Also Read: SUTRA PIC India Program


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