HEAT DOME

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Context:

Due to the heatwave-like conditions, 20 women tea garden workers collapsed in a tea estate in Dibrugarh’s Moran.

What is a heat dome?

A heat dome is a type of high-pressure system that forms over a large area in the atmosphere, and causes extremely hot and dry weather conditions. The system traps hot air and prevents it from flowing to rise and cool. This air then becomes compressed and heats up, leading to a dome-shaped area of hot air that can persist for several days or even weeks.

Mechanism

Heat domes can be characterised by a large area of high pressure, is created by sinking air that warms as it descends. Under a heat dome, the air can become stagnant and not move much, which allows the heat to build up and intensify over time.

High-pressure systems often bring clear skies, which means there is less reflection of sunlight and more absorption of heat. Locations with a lot of land and relatively dry air, such as plains and deserts, serve as a favourable condition for heat domes to form as well.

 

Relation between heat dome and heat wave

Heat domes are just one of the atmospheric conditions that can contribute to the formation of a heat wave. A heat wave is a prolonged period of excessively hot weather, often accompanied by high humidity. Heat waves can occur for a variety of reasons, including the presence of a heat dome. Heat waves can also occur without the presence of a heat dome, such as when warm, humid air masses from the tropics move to an area and stagnate for an extended period.

What causes a heat dome?

A number of meteorological elements work together to create a big high-pressure system in the atmosphere, but the primary reason is upper air circulation and Jet streams. When a high-pressure area builds up within a jet stream, the air descends towards the surface and gets compressed towards the ground, forming a heat dome.

The intensity and duration of a heat dome can also be influenced by other factors, such as the amount of moisture in the air and the presence of other weather systems.

Jet streams

Jet streams is a narrow band of strong wind in the upper levels of the atmosphere. Jet streams are caused by the earth’s rotation and the momentum that air builds up as it moves away from the equator. Each jet stream flows along a boundary between hot and cold, resulting in the polar and subtropical jet streams.

Climate change and heat dome 

Climate change has also been identified among the contributing factors to the increased frequency and intensity of heat domes.

Climate change has led to warmer background temperatures, exacerbating the high-pressure system. Regions that have become drier due to the same, can also create conditions that are beneficial to the formation of heat domes. Additionally, as the icebergs melt, the temperature and moisture patterns in the surrounding regions are influenced.

Impact of heat dome

Heat domes can cause dangerous heat waves causing the temperatures to shoot up. They can also lead to drought conditions and wildfire as the hot and dry weather can quickly dry out vegetation and make it more susceptible to catching fire.

Heat domes can have significant impacts on human health, particularly vulnerable populations such as workers, elderly individuals, children and those with pre-existing health conditions that can be aggravated by extreme heat. 

Recent heat dome effect in Assam

Temperature of around 40 degree Celsius was recorded in Assam in September which is not usual.

Host of factors

The weakening monsoon circulation, poor soil moisture, heavy exposure to sunlight, local factors like heavy deforestation and expanding industrial activity have all contributed towards this heat dome effect.

The main reason cited behind this phenomenon: The absence of monsoonal circulation can be attributed to the imminent collapse of the Gulf Stream, one of the jet streams that controls atmospheric circulation in tropical areas.

Usually, air circulation, emerging from the Bay of Bengal hits the region causing short spells of showers throughout September over the northeastern region and keeps the region cool.

How to combat heat domes?

Heat domes are a natural weather phenomenon and hence, stopping heat domes from forming altogether is not possible.

• Reducing greenhouse emissions: Transitioning to renewable energy sources, improving energy efficiency and promoting sustainable transportation, can be measures in achieving a reduction of greenhouse gas emissions, as it is critical to mitigating the impacts of heat domes in the long term.
• Investing in green infrastructure: Cities can invest in green infrastructure, such as parks, green roofs, and tree planting, which can help reduce the urban heat island effect and provide cooling benefits.
• Implementing building codes and standards: Building codes and standards can help ensure that new buildings are designed to withstand extreme heat and maintain indoor comfort during heat waves.
• Reducing heat-trapping surfaces: Cities can take steps to reduce the amount of heat-trapping surfaces, such as asphalt and concrete, which can exacerbate the urban heat island effect.
• Enhancing public education and outreach: Educating the public about the risks of extreme heat and how to stay safe during heat waves can help reduce the incidence of heat-related illness and mortality.

Must read articles

Heat Dome: https://iasgyan.in/ig-uploads/pdf/HEAT_DOME_compressed.pdf

Heat Dome: https://www.iasgyan.in/daily-current-affairs/heat-dome-31

Heat waves: https://www.iasgyan.in/daily-current-affairs/heatwaves-30

INDIA’S HEAT ACTION PLANS : https://www.iasgyan.in/daily-current-affairs/indias-heat-action-plans#:~:text=Urban%20Planning%20Strategies%3A%20Strategies%20may,abundance%20of%20heat%2Dabsorbing%20surfaces.

URBAN HEAT ISLAND AND URBAN COOL ISLAND : https://www.iasgyan.in/daily-current-affairs/urban-heat-island-and-urban-cool-island

Source

https://climatecheck.com/risks/heat/what-is-a-heat-dome

https://www.downtoearth.org.in/environment/what-is-heat-dome-the-phenomenon-causing-record-temperatures-across-us--88911

https://www.downtoearth.org.in/climate-change/why-is-assam-boiling-hot-heat-dome-effect-say-experts

PRACTICE QUESTION Q.What is a Heat dome? How does it form? Discuss how climate change affects its area and frequency of occurrence with some recent examples. (250 Words)