2020 is stacking up as another year of hot weather. Siberia suffered a heatwave in May, and NOAA is predicting an extra busy hurricane season in the USA. Heat is the enabler for a variety of weather conditions ranging from the unusual to the dangerous.
At a fundamental level, the climate is a result of the planet’s attempts at redistributing heat. Most of our heat comes from solar radiation(sunlight), but some of it is generated inside the earth and radiates outward to the surface. Regardless of the heat’s origin, greenhouse gases in the atmosphere trap heat at or near the earth’s surface. But different regions absorb heat at different rates, making some areas heat up faster than others.
Currents in the atmosphere and oceans are constantly in motion moving heat from hot areas to colder areas. This dynamic system of heat transfer is a key driver of the weather conditions that define a region’s climate.
Greenhouse gases are also important. Without them, the earth’s average temperature would be about -18 degrees Celsius, and a sheet of ice would cover the planet. Since the industrial revolution in the late 1800’s, the level of greenhouse gases in the atmosphere increased by about 50 percent. These additional gases have resulted in an average global temperature increase of slightly over 1 degree Celsius. The earth is a hotter place than it used to be. This extra heat affects our weather.
Siberia
May in Western Siberia is usually chilly, with temperatures below freezing. But this past May brought record-breaking hot weather with temperatures logging in at 20-25 degrees Celsius (68–77 degrees Fahrenheit). This heatwave was proceeded by four months, where temperatures were 6 degrees Celsius above normal. So, what’s the deal?
The short answer is the Arctic polar vortex because the vortex performed a bit of a Jekyll and Hyde act this year. The year started with an extremely strong vortex. Remember, the strength of the vortex is dependent on the temperature differential between the mid-latitudes and the north pole. So heat distribution drives the vortex intensity, and the vortex then influences climate and weather.
The jet stream occurs at the outside edge of the polar vortex. The jet stream is a river of air forming in the upper troposphere a few miles above the earth’s surface and then circling the outer edge of the polar vortex flowing from west to east at speeds that often exceed 100 mph.
When the vortex is strong, the winds flow fast, and the system maintains a more circular shape centered on the north pole. A strong vortex keeps the cold air trapped above the Arctic. This year, the vortex was strong enough to keep the cold tightly bound at the northern edges of Western Siberia. Therefore, most of the region enjoyed much warmer temperatures than usual for the first part of the year.
However, if the vortex weakens, it causes the jet stream to slow down, and the slower moving jet stream is more prone to develop waves or lobes that carry blasts of polar air farther southward and let waves of heat move farther north. Thus, as the vortex weakened this spring, Western Siberia was the recipient of a blast of warm air.
More Hurricanes
Hurricane season starts June 1, and it runs through November 30. NOAA is predicting up to 19 named tropical storms with 10 developing into hurricanes. The historical average is 12 named storms with 6 hurricanes. So far this year we had three named storms before the hurricane season officially started.
Because heat is the critical enabler for hurricane development, the culprit for this potential increase in storms is warmer than average ocean temperatures. As winds sweep across the ocean’s surface, they suck up heat energy from the warm waters. Since warm air holds more moisture than cold air, the winds become heavily saturated with water. But warm air also rises, and this moist, water-saturated air ascends due to buoyancy. Winds then converge on the low-pressure area created by the rising air, and a tropical storm begins.
Other global factors like El Nino Southern Oscillation conditions in the Pacific and an enhanced west African monsoon season also impact hurricane formation in the Atlantic and Caribbean. However, these other factors are also mostly heat-driven.
Weather is mainly about how the earth redistributes heat. When global warming increases the heat content in the oceans and atmosphere, regional weather systems are affected. So, changes in weather patterns and increases in storm frequency and intensity are to be expected as our planet warms.
ArcheanWeb:
Hurricanes more dangerous than in the past (Source: ArcheanWeb) – https://archeanweb.com/2020/06/01/hurricanes-more-dangerous-than-in-the-past/ Also:
The warmest decade (Source: ArcheanWeb) – https://archeanweb.com/2020/05/25/the-warmest-decade/ Also:
Hot and dry in the Western USA, a megadrought in progress (Source: ArcheanWeb) – https://archeanweb.com/2020/04/21/hot-and-dry-in-the-western-usa-a-megadrought-in-progress/ Also:
Sources:
Arctic Circle Temperatures Soar as Siberia Hit by Extreme Heatwave (By Rosie Mccall; Newsweek) – https://www.newsweek.com/arctic-circle-temperatures-siberia-extreme-heatwave-1506441 Also:
Parts of Siberia are hotter than Washington, with temperatures nearly 40 degrees above average (By Andrew Freedman
OAA Predicts ‘Busy’ Atlantic Hurricane Season for Fifth Year in a Row (By Alex Fox; Smithsonian) – https://www.smithsonianmag.com/smart-news/noaa-predicts-busy-atlantic-hurricane-season-fifth-year-row-180974964/ Also:
Busy Atlantic hurricane season predicted for 2020 (Source: NOAA) – https://www.noaa.gov/media-release/busy-atlantic-hurricane-season-predicted-for-2020 Also:
What are El Niño and La Niña? (Source: NOAA) – https://oceanservice.noaa.gov/facts/ninonina.html Also:
Feature Image: April 2020 Heat Map – Source: NOAA – public domain