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A Salute To All The Coasties Out There

We had just passed over Kamchatka, Russia where I took a picture of about 20 of the many dozens of the volcanoes there. The sun angle was low making the volcanoes practically jump out at me.

Along the coast in the foreground you can see wisps of what looks like milk in the water. Those are ice flows that are starting to coalesce into massive sheets.


Volcanoes of Kamchatka

We then headed out over the Aleutians, and as I floated in the cupola juggling three cameras I saw long streamlines of clouds flowing south across Bristol Bay. The clouds then ran into the Alaska Peninsula and there the streamlines met their match.

Downwind of Shishaldin and Pavlof volcanoes, the streamlines became swirls that extended for a thousand miles or more into the north Pacific.


Von Karman Vortex Streets

Those two trails of swirls are Von Karman vortex streets, named after the aerodynamicist who explained the phenomenon. In a nut shell, when airflow of the correct speed passes over a round body (like a volcano, for instance), vortices will be shed alternately from one side and then the other. It’s the same mechanism that can make power or phone lines “sing” in a gale. If you know the diameter of the wire and the pitch of the tone (or in this case the size of the volcano and the spacing of the swirls) you can calculate the wind speed. It’s classic aerodynamics, but on a thousands of miles scale.

Putting the aerodynamics demonstration astern, Kodiak Island came into view and I couldn’t help but think of all those Coasties (members of the United States Coast Guard) down there on fisheries patrol or flying out the Aleutians on a SAR (search and rescue) case.


Moonrise over the Yukon and Kodiak, Alaska

Just as I was thinking about that, the moon started to rise over the Yukon with Kodiak in the foreground. It was a magnificent sight. To all the Coasties in Alaska, and across the US and the world, I salute you. Our service is about saving property and lives on the seas. and you do it exquisitely well.

Fair winds and following seas,

Dan Burbank, Captain, USCG, Ret.
International Space Station Commander
NASA Astronaut