Thursday, May 01, 2008

Wintertime Smokestack Plumes In Fairbanks

Left: The small plume visible on the left can't puncture through the inversion; only the big plume in the center has enough punch to do so.


During winter months, the early-morning surface temperature inversion in Fairbanks, Alaska can be so strong as to act like a perfect lid over the city, inhibiting mixing with the free atmosphere above. Only plumes from powerful sources of heat, like from power plants, can possibly puncture through the lid.

Here are some great pictures of Fairbanks smoke plumes, from a number of different sources (credited when known).

Left: Ice fog over Fairbanks, Alaska in winter 2005. Temperature approximately minus 30F. Joseph N. Hall. Note the mirage at the base of the Alaska Range.

The plume overshoots its final plume rise height, then sinks a bit (I wonder if rapid cooling of the plume due to infrared radiation is responsible for this somewhat unusual behavior - meaning the plume is behaving like a high-temperature flare's plume would behave, and buoyancy flux tends not to be conserved, as it would be at warmer temperatures).


Photo by Eric Engman.

The exhaust from the Aurora Energy power plant breaks through an inversion layer as seen from the Hagelbarger Road pullout off the Steese Highway on Wednesday, Jan. 30, 2008.

Left: Photo by Frank DeGenova.

Some signs of a sinking plume here too. Perhaps there are other explanations of the sinking plumes, like the gravitational fall of the large ice crystals contained within the plume.

Left: Photo by Frank DeGenova.



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