What Causes Heat Waves?

Brighton, England, during a heatwave. Editorial credit: Michaelasbest / Shutterstock.com.
Brighton, England, during a heatwave. Editorial credit: Michaelasbest / Shutterstock.com.

There is no static definition of what a heat wave is. A heat wave is hard to define as temperatures can vary so greatly from country to country. For example, in the Netherlands, a heat wave is the period between which the maximum temperature exceeds 25 degrees within five consecutive days in which three days within this period experience a temperature exceeding 30 degrees. Similar countries that use this definition of heat wave include Belgium and Luxembourg. In Denmark, a heat wave is experienced when at least 50% of the nation is experiencing temperatures exceeding 28 degrees in a minimum of three consecutive days. However, in many of the world's warmest countries, these temperatures would be typical, and would not register as a heat wave at all. It's easiest to just describe a heat wave as a prolonged or an extended period of abnormally hot weather conditions.

What Causes a Heat Wave?

A heat wave is said to occur when high pressure moves into a new area and remains there for several days or even weeks. Heat waves are normally experienced during the summer in the Southern and Northern Hemispheres. During the occurrence of heat waves, air from the upper part of the earth’s atmosphere is dragged towards the earth’s surface. At this level, the air is compressed and as a result, the temperature increases.

As the air is compressed and temperature increases, it leads to the increased pressure in this region that makes it almost impossible for other weather systems to occupy the region. Because other weather systems cannot move to this high-pressure region, it makes the heat waves last for several days, and sometimes it lasts for weeks.

Heat waves are generally experienced during summer because, during this time, the weather patterns take longer than usual to change unlike in winter. Heat waves can pose a danger to public health. Some of the common health problems caused by heat waves include heat edema, heat rash, heat syncope, and heat cramps. It is approximated that 6,200 Americans are hospitalized every summer due to excessive heat waves. During the occurrence of this weather system, it is essential for one to stay out of sunlight, especially during the hottest times of the day. Staying out of the sunlight will significantly help the body avoid excessive sweating and consequently prevent health complications. One can also take precautionary measures such as drinking plenty of water and avoiding any form of strenuous activity. 


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