Nature Notes – January 2024

by Andy Johnston

polar stratospheric cloudsThe early winter weather has been dominated by gales bringing warm weather from the west due to a strong El Nino. Ultimately this system invariably brings a drastic change to drier and colder weather in the latter half of winter and early spring. Currently high up in the atmosphere a vortex of very strong winds keeps intensely cold polar air bottled up above the Arctic. Recently these stratospheric winds have been weakening, and if they grow too weak and go into reverse, cold polar air will descend and penetrate our weather system, and at worst could see the return of the ‘Beast from the East’.

Another portent of cold weather to come was the glorious display of nacreous clouds or mother of pearl clouds, just after sunset on 21 December. These are some of the highest clouds to be seen, 15 to 20km up in the stratosphere where the air is dry, and are exceptionally rare. Sunlight makes the ice crystals in the clouds glow pearl coloured, and they are most unusual at our latitude. This autumn has seen a bumper crop of haws, very much appreciated by wildlife. Folklore warns of cold winters and snows if there are plenty of hawthorn berries; ‘When the hawthorn has too many haws, we shall still have many snaws’. There you have it, winter draws on!!