Syllabus: General Studies paper 1 (Geography)
Canada broke a national heat record on june 27, when the temperature in a small town in british columbia reached almost 116 degrees fahrenheit. At least 134 people have died suddenly in canada.
- A historic heat wave is prevailing in the pacific northwest.
- Heat waves are generally the result of trapped air.
Cause behind heat wave:
The heat wave was caused by what meteorologists described as a dome of high pressure over the northwest and worsened by human-caused climate change
- Heat domes:heat domes or sprawling ridges of high pressure are a staple of summer. They bring copious sunshine and sinking air that heats up as it is compressed.
- As the ground warms, it loses moisture, which makes it easier to heat even more.
- And in the drought-ridden west, 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
Favourable conditions for heat wave:
- Transportation / prevalence of hot dry air over a region: there should be a region of warm dry air and appropriate flow pattern for transporting hot air over the region.
- Absence of moisture in the upper atmosphere (as the presence of moisture restricts the temperature rise).
- The skyshould be practically cloudless (to allow maximum insulation over the region).
- Large amplitude anti-cyclonic flow over the area: heat waves generally develop over northwest india and spread gradually eastwards & southwards but not westwards (since the prevailing winds during the season are westerly to north westerly).
Question: what is heat wave? What is the criteria for conditions to be classified as a heat wave ?