US Heat Wave

  • IASbaba
  • June 30, 2021
  • 0
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  • GS-3: Conservation, environmental pollution and degradation, environmental impact assessment

US Heat Wave

Context: Recently, US Weather service has issued another excessive-heat warning for much of Washington state and North East.

  • In most parts of the country, temperatures must be above the historical average in an area for two or more days before the label “heat wave” is applied to a hot spell.
  • But the definition can vary by region; in the Northeast USA, it is defined as three straight days in the 90s or above.

What causes a heat wave?

  • Heat waves begin when high pressure in the atmosphere moves in and pushes warm air toward the ground. That air warms up further as it is compressed, and we begin to feel a lot hotter.
  • The high-pressure system pressing down on the ground expands vertically, forcing other weather systems to change course. It even minimizes wind and cloud cover, making the air more stifling. 
  • This is also why a heat wave parks itself over an area for several days or longer.

What is a heat dome?

  • As the ground warms, it loses moisture, which makes it easier to heat even more. And in the drought-ridden West USA, there is plenty of heat for the high-pressure system to trap.
  • As that trapped heat continues to warm, the system acts like a lid on a pot — earning the name “heat dome.” 
  • In the Pacific Northwest, the heat and the drought are working in concert, exacerbating the problem and causing temperature records to fall day after day.

Why is it hotter than normal in North America?

  • We have long known that the world has warmed by more than 1 degree Celsius (about 1.8 degrees Fahrenheit) since 1900, and that the pace of warming has accelerated in recent decades. 
  • The warmer baseline contributes to extreme-weather events and helps make periods of extreme heat more frequent, longer and more intense.
  • Magnified effect of paved and concrete surfaces in urban areas and a lack of tree cover.
  • Urban heat island effects can make ambient temperatures feel 3 to 4 degrees more than what they are.

Health Impacts of Heat Waves

  • The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.
  • It also causes heat cramps, fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
  • The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

Way Forward

  • While climate change does have a strong link with the occurrence of extreme weather events, it isn’t the cause for extreme weather events. Episodes of heat waves are growing more common as climate change intensifies. Therefore, the intensity and frequency of heatwaves can be reduced if the global community adopts and adheres to a lower emissions scenario in the future.

Connecting the dots:

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