@Gkikas-LGPZ Thank you for your respond. It was edited. My mistake.

@Gabou971 Thanks for reminding the altitude. My mistake :)

In the previous posts we wrote about all low-level clouds, like Cumulus, Stratocumulus, Stratus and Cumulonimbus. All of the low-level clouds have their base under 2 000 m (6500 ft). Let's recapitulate and add some new information about them. And in the first picture, there are symbols for all of the low level clouds used in meteorology.

Cumulus is a nice cloud that usually travels alone. Its top is often in the shape of a cauliflower. The base is darker and flat, but the body can be really white. It is created by convection of saturated air and condensation of the water vapour.

Cumulus humilis is a flattened Cumulus that cause no precipitation. It usually appears in front of a summer anticyclones.

Cumulus mediocris has its horizontal size quite similar to the vertical size. In spring, Cumulus mediocris can reach the zero isotherm and water drops or little ice crystals can appear. They can fall down in showers. But in summer is the zero isotherms higher and only very rare precipitation is possible.

Cumulus congestus has its vertical size much bigger than the horizontal. Therefore it is sometimes called towering cumulus. This species quite often grow in the size of Cumulonimbus and so it can signal a storm ahead!

Cumulus fractus is only rest of a Cumulus after precipitation.

Stratus is a grey cloud layer with a uniform base that can cause light rain, drizzle or little ice crystals. You can recognize a Sun through this cloud. It can transform into fog and back as it goes to the mountains. It is created by radiative cooling, a transformation from fog or by turbulence. It usually appears in winter in foothills at the back of an anticyclone together with an inversion.

Stratus nebulosus is a typical Stratus cloud and Stratus fractus is what remains after it.

Stratocumulus is grey or whitish bigger or smaller groups or layers of clouds. It looks like it consists of many smaller clouds. It usually causes no precipitation, but light rain or snow can occur. Sun is mostly not visible through this cloud type. It is created by a combination of Stratus and Cumulus generation, so by radiative cooling and convection. Stratocumulus can come before bad weather (before a storm, with a warm front,...)

Stratocumulus stratiformis is a lightly deformed flat layer, Stratocumulus lenticularis looks like a lens with a smooth surface, Stratocumulus castellanus have towers that increases and grows from its base and Stratocumulus volutus is a big rolling cloud.

Cumulonimbus is a huge and dense cloud with great vertical magnitude. A part of its top is flat and smooth or fibrous that looks like an anvil. Is it a typical precipitation cloud that hides both water drops and ice crystals in it. The precipitation is very intensive, heavy rain and thunderstorms. It is common in summer, in winter is the tropopause low and therefore the Cumulonimbus is smaller but possible. It is created from Cumulus congestus and often goes before a cold front.

Cumulonimbus calvus is a lower stage of Cumulonimbus. Its top is like cauliflower and sometimes it can spread horizontally and create a shape of a veil or a canvas.

Cumulonimbus capillatus is a mature stage that has a full anvil formed. It is a cloud of bad weather (thunderstorms).

If you want to learn more, see the articles about the species of each types.

@Gabou971 Yes, I think it is. Amazing look at it!

As the last low-level cloud species will be Cumulonimbus capillatus (Cb cap), which is a really huge storm cloud. It is still counted as a low-level cloud because its base is usually below 2 km hight, but its top can reach the tropopause, which is about 10 km high in the middle latitudes and in equatorial areas it is about 16 km high. In extremes, the Cumulonimbus reaches the lower stratosphere at 20 km altitude. So, how does it look like, and why should we be careful?

Cumulonimbus capillatus looks like an anvil because it has a wide top which looks like a hair. And a word "hair" in Latin is "capillatus"! It sometimes remotely resemble a ruffled hair on a cloud, which can be long through all of the clouds. It is a nice look at it, but only from a distance.

When it comes to precipitation, Cumulonimbus capillatus rarely causes showers. Usually, it makes heavy rain, thunderstorms, strong wind and hail. For all this, it is one of the most dangerous clouds you can spot in the sky!

Cumulonimbus is more likely to occur in summer and in some cases it comes with a cold front, rarely with a warm front.

Watch out for the Cumulonimbus capillatus and send your photos!

As was mentioned in the previous post, Cumulonimbus is a heavy big bad cloud. But this cloud can come in a quite nice species - Cumulonimbus calvus (Cb cal).

Cumulonimbus calvus is the most pleasant species of Cumulus. It is without any fibrous and striated parts. The top of the cloud looks quite flattened and looks like a white mass without sharp outlines. Basically, you can mistake it for Cumulus congestus, but it is just a way bigger then any Cumulus and it can even form from Cu con!

This light version of the beast brings usually lighter rain in a form of showers, but it can also cause heavy rain, strong winds, hail or even storms. Although it is not so extreme like with its brother Cumulonimbus capillatus, which will be in the next post!

Send your photos of a thunderstorm cloud!

The last cloud type in the low-level troposphere is Cumulonimbus, the highest cloud. How can we recognize it and most importantly what does it mean when Cumulonimbus is coming our way?

Cumulonimbus is a heavy and dense cloud that can reach from the low level up to the high-level troposphere (from 1 km to 12 km). It is a white and grey massive cloud tower with smooth, fibrous or striated parts of its upper portion. The base is often really dark and bad looking at all.

Image credits: jacinta lluch valero

Usually, the Cumulonimbus brings heavy rain that can last for hours! And there's more! Cumulonimbus is responsible almost for every thunderstorm, tornados and other dangerous phenomenona. So, when you see it, find yourself a good shalter, stay at home or hide in a bar.

Have you seen the Cumulonimbus at its best? Send your photos!

Image credits: Piyapon Poottima

@Gabou971 That is a perfect picture. I was in the Julian Alps in summer 2017 and the landscape is just amazing. Thank you for such a nice photo!

Considering stratus nebulosus, Stratus fractus is quite small and not so much dangerous. What about a closer look at this last low-level species?

Stratus fractus (St fra) is irregularly shaped with outlines that change very fast. At first sight, it may look like a Cumulus, but it is less white, less dense and mainly it is less vertically developed. Stratus fractus is created by turbulence, not rising warm air. Therefore, it is more flat and large compared to Cumulus fractus.

Stratus fractus is rarely connected to precipitation but usually comes with precipitation clouds, e.g Nimbostratus. And if it rains from Stratus, then it is only light rain.

Have you ever taken a photo of this torn-apart cloud? Send them!

The previous post introduced the last low cloud type - Stratus. The most common form of it is Stratus nebulosus (St neb). Let's have a look at this huge species.

Stratus nebulosus is, in general, recognizable by its look. It looks like enormous fog hovering above our heads. In mountains, it can even quietly change from fog to cloud and back again. Despite its magnificent look, it can cause several problems with visibility. It is a grey, uniform fog that can cause trouble for example at airports.

Stratus nebulosus can cause some light precipitation such as drizzle or light snow. More probability to form Stratus nebulosus is in winter right before sunrise or in the afternoon.

Have you met this cloud for example on the skiing? Send you photos!

Poznámka pro adminy: chybný náhled v seznamu článků, zobrazuje se úplně stejně jako následující (později vypublikovaný) článek.