The Arctic polar vortex is a strong band of winds in the stratosphere, surrounding the North Pole 10-30 miles above the surface.
Photo: NOAA
By Kevin McKeon, Maine Master Naturalist
Picture the eye of a hurricane, with its spinning eyewall surrounding a relatively calm interior. Now, put this eyewall above the Arctic Circle. That’s something like the polar vortex we’ve been hearing about. This spinning cylinder begins about 10 miles above the Earth’s surface near the troposphere/stratosphere boundary and extends another 20 miles through the stratosphere and into the mesosphere. This year-round, natural air mass formation is usually about 600 miles wide, but sometimes it gets over 1,000 miles wide. It strengthens in winter, building faster winds and a smaller diameter, and weakens in summer due to changes in the temperature differences between the cold Arctic and warmer temperate air masses. The Arctic’s tilting away from the sun during winter chills its air mass during the famous long arctic winter night.
In the lower atmosphere, below and further south from the polar vortex, the polar jet stream similarly forms — encircling the vortex and, along with Earth’s rotational forces, holding the vortex in place. Both air masses are vortexes: The polar jet stream is the tropospheric vortex, and the polar vortex is more accurately termed as the stratospheric vortex, describing the atmospheric regions wherein the vortexes occur. And both flow from east to west (westerly); looking down from space above the Arctic, they flow counterclockwise. Normally, this temperature differential during our winter is sufficient to keep the vortex strong and healthy and hold the frigid air above the Arctic region. Global warming, however, is disrupting this weather-moderating vortex by impacting the Arctic’s overall climate.
Warming reduces arctic sea ice coverage and allows solar rays to penetrate and warm sea water instead of reflecting the ice back into the atmosphere. This warms the arctic waters, melting more sea ice, increasing water surface area, increasing solar ray penetration to warm and melt even more ice, perpetuating arctic warming. The warming region causes land-based ice sheets to evaporate and/or melt, reducing ice coverage. The decreasing weight of the ice sheets allows Earth’s magma and gas chambers to creep closer to the surface — like bubbles rising to the top of an opened soda bottle — increasing volcanic activity. As increasing amounts of volcanic ash spew out and fall to the ice sheets, it creates a darker surface allowing solar rays to penetrate rather than to reflect off, which melts even more ice at the surface. This creates lakes of melted water — with black volcanic ash — which increases solar absorption perpetuating ice melting and lake growth. What solar radiation is reflected off the ice is captured by the Arctic’s increasing levels of greenhouse gases, warming the atmosphere. These factors all combine to warm the Arctic region four times faster than any other area on Earth, and the lowered temperature differential weakens the vortexes.
Yet another phenomenon called sudden stratospheric warming (SSW) can disrupt the vortexes. SSW is a rapid warming of the polar vortex’s air mass caused by surges of upward air acting like horizontal waves, crashing over the polar vortex, weakening it and causing major weather disruptions weeks to months later. A SSW happened just a couple of months ago in late November/early December — a rare, early-season SSW event and major factor of not only last week’s cold, snowy weather, but is projected to continue affecting our weather into February — with disruptions likely worldwide as well. As arctic warming increases, SSW events will become more common — along with the weather extremes they bring.
So, these are some of the events that conspire to lower temperature differences between the arctic and temperate air masses, weakening the winter vortexes, and increasing SSW events. These fluctuating weaknesses manifest as undulating waves in the vortex: Looking down from space again, these waves appear as elongations or lobe-like arms in the normally healthy circular vortex. These lobes reach southward, carrying Arctic cold air with them. Sometimes, these lobes stretch far enough to reach and react with the relatively warm, moist air masses in central United States influenced by the California coast and Gulf of Mexico waters, and in Eastern Europe by the warm Gulf Stream. Thus, powerful storms are created, carrying rain, ice, snow, and high winds. This is what is our friends and families experienced last weekend in South-Central and South-Eastern U.S. regions.
Many scientists are advocating for increased awareness of the several tipping points relating to Earth’s weather and climatic extremes. The tipping point we’ve all heard about is the increase in global average temperatures. Others are the coral reefs dying, ocean acidification, rain forests depletion, ice sheet melting, permafrost melting, and atmospheric CO2. When these tipping points are reached, they tend to feed themselves — a type of self-amplification, inducing critical ecological systems to falter, and creating an irreversible cyclone of climatic, economic, and ecological upheaval. Knowing this, we all can prepare to varying extents, and learn ways to mitigate our individual “carbon footprint” upon our Earth home. The scientists are speaking — we really should listen. One relatively easy — and healthy — thing to do: Eat less animal meat. This industry contributes up to 20% towards global warming, so maybe, have a couple of meatless meals a week. The money saved from the supermarket can be put towards fewer but tastier locally farmed meaty meals!
The post How the Polar Vortex Relates to Our Snowy Winter appeared first on Sanford Springvale News.
