Really? W/ Liam Healy: Urban Heat Islands

Digital Desk

Charleston, WV (WVNS) — West Virginia only has a few ‘big’ cities: Charleston, Huntington and Morgantown, just to name a few of the well-known ones. But much of the state is either rural or suburban, so the term ‘Urban Heat Island’ may be a new one for many. But in other states with more and more of their populations living in cities, the term is becoming a familiar one during the summertime.

The ‘Heat Island Intensity Score’ for Charleston, WV shows how these factors contribute to higher heat within the capital city. Overall Charleston is on average 6.3-degrees warmer than surrounding rural areas as a result of the above factors. Image Credit: Climate Central

Simply defined an ‘Urban Heat Island’ is a measurable increase in urban air temperatures, resulting primarily from the replacement of vegetation with buildings, roads, and other heat-absorbing infrastructure. Generally, most building materials found in cities have low albedo or low reflective properties and absorb heat instead of reflecting it. Some examples include asphalt, concrete and even bricks. These will trap heat during the day and radiate it back into the surrounding air, causing temperatures to surge 15 to 20-degrees higher than they would be in a rural setting.

There are other contributing factors to the increased heat found in these big cities. Tall buildings can restrict the movement of air creating stagnant air that can heat quickly; higher concentrations of vehicles, electricity usage, and other machinery can also add more heat into the already hot air.

A graph showing the various differences in temperatures between different types of land use. The hottest temperatures are often found during the day and night across urban and industrial areas. Image Credit: Climate Central

Suburban settings can face similar issues, depending on how built up the area is, but the increase in space between structures and having more plants and green spaces help to provide opportunities for heat to escape. One of the reasons having more plants, such as grass and trees, in an area helps lower temperatures is that when they absorb energy from the sun, plants go through the process of evapotranspiration. Essentially when the plants release water vapor, they use heat from the surrounding air to change the state of the water from a liquid to a gas, thus cooling the air around them.

By taking notes from how suburban landscapes cool themselves, we can apply that to the cities of the future. Utilizing spaces that are often forgotten about such as rooftops, new green areas such as gardens and parks, can be added to reduce the capture of heat and introduce more natural cooling. Other proposed solutions include introducing materials with higher albedos to rooftops and other surfaces reducing the amount of heat absorbed. This can also help to reduce heat released by air conditioners by keeping buildings cooler.

Small changes can have big impacts that might just save lives as heatwaves become more dangerous due to climate change as evidenced by the major heatwaves experienced in the Pacific Northwest in 2021.

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