Recently, the Pacific Northwest and some parts of Canada experienced an unusual surge in temperatures, marking a record as high as 47 degrees. The reason behind this momentous heat wave is a meteorological phenomenon, labeled as a “heat dome”.
Understanding the Phenomenon of a ‘Heat Dome’
A heat dome originates from significant fluctuations in ocean temperatures. During this process, known as convection, the temperature gradient prompts more warm air, heated by the ocean surface, to elevate over the ocean. This heated air, driven by prevailing winds, moves eastwards. The thermal air is then caught in the northern shifts of the jet stream, which directs it towards land. As the air descends, it induces heat waves.
In essence, a heat dome behaves like a lid on a pot, effectively sealing high pressure and heat within a region. Its formation is commonly observed during La Niña years such as 2021, when waters are cooler in the eastern Pacific and warmer in the western Pacific.
Journey of Jet Streams
Jet streams can be described as relatively narrow bands of potent wind present in the upper levels of the atmosphere. These winds typically blow from west to east, but the flow often deviates to the north and south. A significant change in ocean temperature from west to east is the foundation for the creation of heat domes.
Impact of the Western Pacific’s Rising Temperatures
Over the past few decades, the western Pacific Ocean’s temperatures have been steadily climbing. This is notable as these temperatures exceed those in the eastern Pacific. Heat domes also impede cloud formation, thus enabling more solar radiation to reach the ground surface.
The Reality of Heat Waves
A heat wave characterizes a period when temperatures unusually exceed the normal maximum for more than two days. While these generally occur between March and June, some have been known to persist until July. Whether accompanied by high humidity or not, heat waves potentially span vast areas, thus exposing a significant number of people to hazardous heat conditions.
Interconnections Between Wet-bulb Temperature and Human Health
The body possesses an inherent ability to remain cool under high temperatures as long as it can produce sweat which evaporates quickly. Wet-bulb temperature (WBT) represents threshold combining heat and humidity beyond which humans cannot withstand high temperatures. Crossing this limit may lead to health problems such as heat stroke, heat exhaustion, sunburn, and heat rashes, with the potential risk of fatalities.
Potential Repercussions of a Heat Dome
Heat domes have multiple far-reaching impacts. For those without air conditioning, indoor temperatures may become unbearably high, leading to sudden fatalities. They can also inflict damage on crops, desiccate vegetation, and potentially cause droughts. Additionally, the increase in overall energy demand, especially for electricity, results in higher rates. It’s also noted that heat domes could accelerate wildfires, resulting in substantial land destruction.
The Association Between Climate Change and Heat Domes
Increasingly, scientists are tracing a connection between extreme heat waves and climate change. According to a survey by the National Oceanic and Atmospheric Administration (NOAA) in 2017, average US temperatures have risen since the late 19th century. However, attributing specific contemporary events to climate change remains a challenging task due to the difficulty in eliminating other potential causes or natural variability completely.
Last Modified: February 15, 2024