Why is this island smoking? This image was captured by the…

Why is this island smoking?

This image was captured by the Suomi NPP satellite and shows a place north of the Arctic Circle (76° North) known as Bennett Island. As you can see, it’s smoking.

This island is something of a marvel for that reason. It’s not emissions from an active volcano and to the best of most people’s knowledge the island isn’t inhabited. Yet, for decades, these plumes and clouds have been recognized as appearing from the island.  

A couple other ideas were proposed; that the plume was methane, seeping up from the Arctic Ocean floor, or the plume was caused by some sort of secret military operations on the island during the cold war.

The answer is less exciting than that, or at least it might seem that way to anyone other than atmospheric scientists. An expedition in the early 1990’s found that the island is causing a series of orographic clouds to form as a consequence of its height through a fairly unique but well-understood process.

The island itself is only a few hundred meters above sea level but it is causing clouds to form at a height of several thousand meters. These clouds form when the atmosphere is quite stable in the region and there is a prevailing wind direction. To get over the island, wind currents have to move upwards by several hundred meters when they run into it.

As a consequence, every layer of the atmosphere above the island is disturbed; the lower levels push the air levels above them upwards until eventually there is a disruption at a level where clouds can form.

When moist air in the atmosphere above this island is pushed upwards by that small amount, it cools off slightly and moves to slightly lower pressure…just enough of a change to cause the formation of clouds if there is enough water in the atmosphere.

So this phenomenon, like most cloud layers, isn’t anything nefarious, it’s a consequence of the correct set of atmospheric conditions.

-JBB

Image credit: NASA/EO

earthobservatory.nasa.gov/IOTD/view.php?id=82213

Read more

http://www.lbl.gov/Science-Articles/Archive/arctic-plume.explored.html