HEAT WAVES

HEAT WAVES

CONTEXT

• The Indian Meteorological Department (IMD) has issued warnings in anticipation of severe heat wave across several states in the country, including Delhi, Uttar Pradesh and West Bengal.

WHAT ARE HEAT WAVES ?

• According to IPCC , heat wave as “a period of abnormally hot weather, often defined with reference to a relative temperature threshold, lasting from two days to months.
• A heat wave is considered extreme weather, and poses danger to human health because heat and sunlight overwhelm the human body’s cooling system.
• Heat waves can usually be detected using forecasting instruments so that a warning can be issued.
• Heatwaves often have complex effects on human economies, due to less productivity of workers, disruption of agricultural and industrial processes and damage to infrastructure not adapted for extreme heat.

ORIGIN OF HEAT WAVES

• Heat waves form when high pressure aloft (from 10,000–25,000 feet (3,000–7,600 metres)) strengthens and remains over a region for several days up to several weeks.

• Summertime weather patterns are generally slower to change than in winter.
• As a result, this upper level high pressure also moves slowly.
• Under high pressure, the air subsides (sinks) toward the surface, warming and drying adiabatically, inhibiting convection and preventing the formation of clouds.

IMPACT OF CLIMATE CHANGE

• Heatwaves over land have become more frequent and more intense since the 1950s due to climate change in almost all world regions.
• Higher growth in greenhouse gas emissions would cause more frequent and severe temperature extremes.
• A heatwave that would occur once every ten years before global warming started, now occurs 2.8 times as often.
• Under further warming, heatwaves are set to become more frequent.
• An event that would occur each ten year, would occur every other year if global warming reaches 2 °C.

IMPACTS OF HEAT WAVES

• Heat waves significantly threaten agricultural production.
• If a heat wave occurs during a drought, which dries out vegetation, it can contribute to bushfires and wildfires.
• Heat waves can also contribute to severe flooding. The record-breaking heat wave that afflicted Pakistan beginning in May 2022 led to glacier melt and moisture flow
• Heat waves can and do cause roads and highways to buckle and melt, water lines to burst, and power transformers to detonate, causing fires.

SYLLABUS: PRELIMS, ENVIRONMENT

SOURCE: THE STATESMAN, WIKI