#cloud-appreciation

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Sunset and Showers by Tim Haynes Via Flickr: Rain falling over Crieff, Strathearn.

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Bass Rock by Tim Haynes Via Flickr: The Bass Rock sits just beyond the mouth of the Firth of Forth in East Lothian, a volcanic outcrop now uninhabited but previously home to a hermit.

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Clouds and Mountains by Tim Haynes Via Flickr: Mor Bheinn, Strathearn, from outside St Filan's.

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It was a pretty decent red sunset but seeing polar stratospheric (nacreous) clouds for the first time is the icing on the cake. Awesomely beautiful.

According to wikipedia, polar stratospheric clouds are clouds in the winter polar stratosphere at altitudes of 15,000–25,000 meters (49,000–82,000 ft). They are best observed during civil twilight when the sun is between 1 and 6 degrees below the horizon. They are implicated in the formation of ozone holes. The effects on ozone depletion arise because they support chemical reactions that produce active chlorine which catalyzes ozone destruction, and also because they remove gaseous nitric acid, perturbing nitrogen and chlorine cycles in a way which increases ozone destruction.

Nacreous Clouds It was a pretty decent red sunset but seeing polar stratospheric (nacreous) clouds for the first time is the icing on the cake.