Clouds

I was away the week before last, soaking up some sunshine in North Yorkshire on a campsite with my dog. As a consequence of being outdoors for most of the day, I was struck by how often I found myself gazing at the heavens. The slightly flatter landscape meant that I could see much further in a single view and the clouds in particular were astounding. I took quite a few photos as proof… as you can see.

NASA tells us that a cloud is made of water drops or ice crystals floating in the sky. There are many kinds of clouds. Clouds are an important part of Earth’s weather. The sky can be full of water. But most of the time you can’t see the water. The drops of water are too small to see. They have turned into a gas called water vapor. As the water vapor goes higher in the sky, the air gets cooler. The cooler air causes the water droplets to start to stick to things like bits of dust, ice or sea salt.

Most of the water in clouds is in very small droplets. The droplets are so light they float in the air. Sometimes those droplets join with other droplets. Then they turn into larger drops. When that happens, gravity causes them to fall to Earth. We call the falling water drops “rain.” When the air is colder, the water may form snowflakes instead. Freezing rain, sleet or even hail can fall from clouds.

Clouds are important for many reasons. Rain and snow are two of those reasons. At night, clouds reflect heat and keep the ground warmer. During the day, clouds make shade that can keep us cooler. Studying clouds helps NASA better understand Earth’s weather. NASA uses satellites in space to study clouds. NASA also studies clouds on other planets.

The present international system of Latin-based cloud classification dates back to 1803, when amateur meteorologist Luc Howard wrote The Essay on the Modification of Clouds. The International Cloud Atlas currently recognizes ten basic cloud “genera,” which are defined according to where in the sky they form and their approximate appearance. High-level clouds typically have a base above about 5 000 meters (16 500 feet); middle-level clouds have a base that is usually between 2 000 and 7 000 m (6 500 to 23 000 feet); and low-level clouds usually have their base at a maximum of 2 000 m (6 500 feet).

Most cloud names contain Latin prefixes and suffixes which, when combined, give an indication of the cloud’s character. These include:

–   Stratus/strato: flat/layered and smooth

–  Cumulus/cumulo: heaped up/puffy

–  Cirrus/cirro: feathers, wispy

–  Nimbus/nimbo: rain-bearing

–  Alto: mid-level (though Latin for high)

The 10 genera are subdivided into “species,” which describe shape and internal structure, and “varieties,” which describe the transparency and arrangement of the clouds. In total there are about 100 combinations.

It also proposes some new “special clouds,” such as Homogenitus (from the Latin homo meaning man and genitus meaning generated or made). Its common names include Contrails (from aircraft).

The new International Cloud Atlas is a tribute to the generosity of the Hong Kong Observatory and the dedication and enthusiasm of a special WMO Task Team, which spent nearly three years revising the text and collecting and classifying images and data. It increases and enriches our understanding of clouds and will serve as an invaluable resource for many years to come.

I love the way these pitted forms just filled the entire sky.

Dramatic and beautiful, we’re so lucky to have such variety in our skies.

A few slinky and seductive, low lying clouds coloured by the setting sun.

People get very excited about UFO shaped clouds, here’s some strange examples I found online.

Fortunately I didn’t encounter many of these heavy rain clouds last week. Someone up there must have been looking after us !

Before the drama of the back-lit effect at the day’s end.

Whilst writing my blogpost today, I found out that there’s a Cloud Appreciation Society where people from across the world post photos of the clouds they’ve spotted, another featuring painted clouds on Outdoor Painter. Discovering and capturing a great cloud formation is obviously more than just a fine art !

Many thanks to NASA and the World Meteorological Organization for the technical info on Clouds used in my blog today. Do you have any great cloud photos or memories ? I will be talking more about my holiday travels during the next couple of weeks so do check back in.

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