What is an inversion? Well, typically, as you increase in elevation or height above the surface of the earth, the air gets cooler. Typically, for every 1,000 ft. you rise in the atmosphere, the temperature drops by about 3 °C (~ 5 °F). In certain instances, though, the opposite is true, and the temperature rises as you get higher above the surface of the earth. That was the case this morning.
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| (NWS Burlington) |
Take a look at the above image, which shows temperatures at various sites in Vermont at 7:00 AM this morning. Mt. Mansfield, which is the state's highest point at an elevation of 4,393 feet, had the highest temperature at 7:00 AM, a balmy 19 °F. Note that many other locations saw temperatures below zero.
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| (NWS Gray) |
The same held true in New Hampshire. Mt. Washington, the highest point in New England (6,288 feet), had a morning temperature of 19 °F, which was warmer than the southern NH coastal town of Portsmouth, NH (11 °F).
Here is a look at the HRRR model sounding for this morning. In this image, the y-axis, which is pressure, can be thought of as height above the surface of the earth (pressure decreases as height increases). The x-axis is temperature in °C. The red line, which represents temperature, clearly shows a rapid increase in temperature as height increases, something that happens in an inversion.
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| (Tropical Tidbits) |
What caused the inversion this morning? Last night was a very clear night, with virtually no clouds in the sky. The earth emits radiation (or heat) from its surface, and radiation can easily escape when there are no clouds. The emitted radiation cools the surface of the earth, and when lots can easily escape, the surface of the earth can cool to a greater extent than typical, thus causing an inversion. Additionally, cool, dense air from the higher elevations can easily "sink" into valleys on inversion nights, enhancing the inversion.
Today, you'll see the temperature inversion dwindle as the sun rises and the surface of the earth warms due to the suns radiation.
I learned a couple of things.
ReplyDeleteFor every increase in elevation of 1,000 feet the temperature drops by 5 degrees Fahrenheit.
When you experience an inversion, the temperature increases with elevation.
Two interesting facts.
M
Interesting observations. The increase of 5 °F for every 1,000 feet is a general rule of thumb, although it depends also on the humidity and temperature of the atmosphere.
DeleteHere is some more info on this neat topic:
https://www.britannica.com/science/lapse-rate