I’m learning to know unusual clouds when I see them, and also to understood which clouds mean instability on the horizon. Sometime in the next few days, there will be some wind and rain at times.

I’m also learning to do some weather predictions, a new and hopefully accurate reading of clouds and the weather that follows them.

Yesterday and today, I saw some beautiful clouds, they call these Cumulus Congestus. The meteorologists also call them “aggressive” clouds, who would have thought.

As rising moisture matches the temperature of warm,  stable surrounding air, it will tend to spread out, into strataform clouds, rather than grow upwards, as cumulus and other clouds do.

But if the rising moisture remainds surrounded by cooling air, as apparently happened today, it will continue rising to form cumuliform clouds, a certain sign of atmospheric instability – and also an excepionally beautiful cloud.

There are many limits to the growth of cumulus clouds, such as wind shear on one side of the other, evaporation from above, or surfaces on the ground reflecting changing levels of head radiation.

These clouds are are called aggressive, but they are also beautiful, and sit up in the sky grandly. They are deceptive,  there is a lot going on that we can’t  see, it’s often quite turbulent and means turbulence is close behind.

When a day’s worth of uplift – hot air and wind rising – “energetic” cumulus clouds can grow extremely large, as seen in the photograph – it was late afternoon.

Their great white “convective” turrets can go as high as a mile in the sky, and will begin to disperse as the skies darken.

(Note:‘Convection clouds’ are ones that form and grow by the process scientists call convection. Cumulus and Cumulonimbus are examples of this type of cloud. Convection in the atmosphere is the way air floats upwards on account of being warmer than the surrounding air. The cloud forms when the air begins to freeze.)

Cumulus congestive clouds don’t last long, but they tower like giants over land and especially, over the sea. Over water, the cumulus clouds continue to grow all through the night.

I went home and checked the weather. I was surprised. It’s been sunny and  hot all day.

There is 70 per cent chance of rain tonight and all through the weekend, and severe thunderstorms predicted for Monday.

The clouds are not just pretty faces. They tell a story, and take a lovely picture.