Riding high on southerly winds

The hummingbird hawk-moth can be mistaken for a bird.
The hummingbird hawk-moth can be mistaken for a bird.

This is a memorable summer for clouds. We’ve had every kind, from those jolly, cotton wool balls to the billowing monsters that soak us to the skin.

We’ve also enjoyed some very warm spells, when hot air from southern Europe has pushed back cooler winds coming off the Atlantic.

Thunderclouds build when cold air collides with warm humid air

Butterflies and moths from the Mediterranean have ridden those southerly winds to our shores — large numbers of painted ladies and red admirals have arrived, along with some exotic moths. Look out for the hummingbird hawk-moth, a large day-flying moth that so resembles its hovering namesake that people swear they’ve seen a bird. And the lovely bordered straw, another moth that feeds in daylight.

New generations of resident butterflies are emerging now. Commas and small tortoiseshells — the offspring of those we saw in the spring — like to nectar on red valerian and the purple spires of lavender and catmint.

Brown ringlets prefer the pale white flowers of bramble bushes. These butterflies of hedge bottoms and woodland glades have chocolate wings, with a neat white circle at the tip.

If you enjoy seeing these fluttering beauties, then join in the Big Butterfly Count. It’s on from July 17 to August 9 and you don’t have to know the names because there’s an identification chart to download. Find out more at www.bigbutterflycount.org <http://www.bigbutterflycount.org>

Cloudspotting

Luke Howard, a pharmacist, was the first to classify clouds. In 1802 he identified three main types: wispy, high-level cirrus, puffy cumulus, and sheet-like stratus clouds. Since then many more have been added. Some are very strange indeed, especially the lone, squashed-bun cloud that looks like a UFO.

Currently, the World Meteorological Organisation is considering a new cloud. If Undulatus Asperatus makes it into the International Cloud Atlas, it’ll be the first new type to be added in over 50 years. The uncanny Undulatus has the appearance of a rough sea, as seen from the seabed. Nobody is sure how this cloud forms.

Although storms have raged inland, so far they’ve passed us by. However it’s not too late for the storm-chasers. Thunderclouds build when cold air collides with warm humid air, a situation that’s not unusual at this time of year.

The voice of the sky god used to be heard in the thunder and his weapons flew as flashes of light. Sometimes his thunderbolts missed the target and plunged into the earth: any “thunderstones” found in the ground became prized amulets, on the principle that lightning never strikes the same place twice. Thunderstones were usually dart-shaped belemnites, smooth fossils that can be black or translucent.

High altitude winds draw mare’s tails on a fine blue sky. These wispy clouds with the ends turned up, along with those neat little clouds like the scales of a fish, are a sign of a blustery weather front approaching: “Mare’s tails and mackerel scales make tall ships carry low sails”.

If the wind changes and hot air returns it could bring more butterflies and moths — even the giant death’s head moth. But while the winds continue their celestial tussle it’s far from clear which one will prevail. Perhaps they’ll take it in turns. After all, a typical British summer is made from sunshine and showers.