

East Lothian Christine K

The Netweather forum has been inundated with photos of beautiful clouds during #StormHenry. Strange green pink/Rainbow/mother of pearl/iridescence colours. Blocky or wave like shapes, more angular than the usual fluffy clouds.

These clouds are higher up in the atmosphere than our usual everyday clouds. They seem to occur when we have very strong winds at the surface, like Henry has provided. You can see them when the sunlight isn’t too strong and so around dusk and after dawn are ideal times when the sunlight still provides the colours but the power of full daylight doesn’t obliterate the stunning iridescence.

Usually these clouds would only be seen in the polar regions but the show recently has been long lived and widely available. Scotland has seen the most vivid scenes but reports have come in from as far south as Norfolk. Nacreous clouds form below -78 °C temperatures. As you go up in the atmosphere, temperatures fall until you get into the stratosphere. If the surface temp is +6C, top of Cairngorm is -4C, then you have to go up very high to see -78C.