Nacreous Cloud (and contrail) by Colin Heggie
In this photo, Colin Heggie captured the multicoloured dreaminess of a nacreous or polar stratospheric cloud, contrasted with a sunset-lit flight’s contrail cloud. Nacreous clouds form in the stratosphere – some 10 kilometres above the Earth’s surface – where it’s extremely dry compared to the lower troposphere. This means clouds rarely form at these high altitudes, but when they do appear, their scattering of light can create these striking rainbow colours.
These clouds only form in extreme cold, when temperatures in the stratosphere drop below -78°C. This makes sightings of these clouds outside the polar regions, such as this cloud that appeared in Scotland, all the rarer. An opportunity Colin was keen not to miss when he spotted the cloud from his home:
“I didn’t want to risk leaving the house for another location as I wasn’t sure how long the cloud would be visible.”
Colin framed the cloud with a plane flying by, leaving a condensation trail of cirrus cloud in its wake, providing a sense of scale in the photo. Persistent contrail clouds can trap heat in the atmosphere, increasing airplanes’ contribution to global warming beyond the greenhouse gases they emit.
Photo location: Whitehills, Scotland, United Kingdom
Photographer based: Whitehills Scotland
Camera: Leica SL, lens: Sigma 150-600mm, setting: 491 mm, f/6.3, 1/200