50 Pics From The Terrible Heatwaves That Happened This Summer

While scorching heat may not seem as dramatic as other natural disasters (read: floods and tornadoes), the U.S. National Weather Service has deemed it the deadliest weather hazard over the past 30 years. It's especially dangerous during summer when the northern half of the planet is tilted toward the sun, and the northern hemisphere receives increased daylight hours and warmth.

When it comes to heat waves, there seems to be no universal definition of the term as it is relative to local weather conditions. But the same National Weather Service refers to it as a period of abnormally hot weather generally lasting more than two days with high temperatures of at least 90 degrees.

Heat waves begin when high pressure in the atmosphere (also known as an anticyclone) builds up, moves in, and pushes warm air toward the ground. That creates a sinking column of air that warms up further as it is compressed. While moisture in the earth can blunt the effects of the heat (the same way our bodies evaporate sweat to cool the body), with so little water in the soil, there isn’t as much to soak up the heat. So as the ground warms, it often dries out, trapping the latent heat already absorbed by the landscape to heat up even more.

Then, the high-pressure system acts as a cap or a lid on a pot, otherwise known as a "heat dome". It even pushes out cooler, fast-moving air currents and minimizes wind and cloud cover, which gives the sun an open line of sight to the ground. It’s also why heat waves place themselves over an area for several days or longer.

To learn more about these sweltering heat waves and the effects they have on our health and the state of the world in general, we reached out to Jessica Kleczka, a climate psychologist, environmental social scientist, and climate justice activist. "The current heat wave in Europe has led to droughts, crop failures and thousands of heat deaths," she told Bored Panda.

"The UK was forced to declare a red weather warning for heat for the first time in history, with temperatures breaching 40°C [104 °F] in London. While there is not enough data on this particular heat wave yet, we know that the last major heat wave in 2018 was made 30 times more likely by climate change, and we can expect similar conclusions to this current extreme weather event," Kleczka added.