Feature Identification » Identifying Atmospheric Features » Cloud Thickness

Visible imagery and the natural colour RGB are the most useful products for determining cloud thickness. The brightness of the clouds generally indicates their thickness. Thicker clouds tend to appear whiter since they reflect more incoming visible light. Very thin clouds can appear translucent in visible imagery and cyan in the natural colour RGB, depending on the time of day.

Visible

EUMETSAT visible over Africa, 1200 UTC 24 Dec 2016

Natural Colour RGB

EUMETSAT natural colour RGB over Africa, 1200 UTC 24 Dec 2016

Here’s how to determine the thickness of different cloud types in visible and natural colour products.

Type

Thickness

Appearance

Cumulonimbus

Thick

Bright white in VIS, cyan in natural colour

Cumulus

Variably thick

Light grey to white in VIS, lighter cyan in natural colour

Stratus

Variably thin

Nearly translucent through mid-grey in VIS, and light cyan to white in natural colour

Cirrus

Thin

Translucent in VIS and light cyan in natural colour

Now it’s your turn to identify cloud thickness.

Question

Question 1 of 2

Drag each label to a cloud of that thickness in the visible image.

Thick
Thin

The whiter the cloud the thicker it is in the visible imagery. The thickest clouds are likely in the Democratic Republic of Congo. The greyer the cloud, the thinner it is in the visible imagery. The cirrus clouds in southern DR Congo are quite thin, as well as the stratus clouds off the coast of Angola.

Question

Question 2 of 2

Drag each label to a cloud of that thickness in the natural colour RGB.

Thick
Thin

You can differentiate between thick and thin ice clouds as well as thick and thin water clouds.

The more saturated the cyan, the thicker the ice cloud is in the natural colour RGB. The thickest ice clouds are likely in the Democratic Republic of Congo, while the cirrus clouds in southern DR Congo are quite thin. The greyer and/or whiter-pink the water cloud, the thinner it is in the natural colour RGB. The stratus clouds off the coast of Angola are quite thin.

Use the image below to differentiate the thicknesses of both water (two darker blue tones) and ice (two lighter blue tones) clouds. Within each particle type, there are two tones, one darker and one lighter. The darker tone is for thicker clouds.

Natural Colour RGB with overlays for cloud thicknesses

This image was made objectively to help you identify the different cloud thicknesses and particle types. This is not an operational product, it is for instruction purposes only.

It’s significantly more difficult, if not impossible, to identify the thickness of all clouds in the other products. For instance, low clouds cannot be seen in the severe convection RGB, so their thickness cannot be determined.

Infrared

In infrared imagery, the thickness of the cloud is best determined by the cloud type, not by the colour of the imagery. Remember colour determines the cloud-top height or temperature in this imagery. In the southeast portion of this image (Central African Republic and Democratic Republic of Congo), you can see thicker convective clouds. In the central portion are cirrus clouds, with thicker clouds in the western portions (Mauritania, Senegal, and Mali). Low-level stratus clouds show up in the northwest portion of the image over the Atlantic Ocean as well as very faintly in the north central portion in Tunisia.

EUMETSAT infrared image over Africa, 1800 UTC 17 Nov 2017

Water Vapour

Similar to the infrared imagery, the thickness of the clouds cannot be determined by the colour of the clouds in the water vapour imagery. It is dependent on the cloud type. Be especially careful with the water vapour imagery as it is hard to determine where the cloud edges are since this is a consistent 1mm of water vapour surface. It is also important to note that low-level clouds are not visible in this imagery.

EUMETSAT water vapour image over Africa, 1800 UTC 17 Nov 2017

Severe Convection RGB

In the severe convection RGB, a central area of yellow within a cloud surrounded by red is very thick. Thin cirrus clouds can be light yellow through red and into pink. The less yellow the cloud, the thinner it is.

EUMETSAT severe convection RGB over Africa, 1200 UTC 24 Aug 2016

Dust RGB

In the dust RGB, dust clouds are magenta. The more transparent the magenta shade, the thinner the dust cloud.

EUMETSAT dust RGB over Africa, 1200 UTC 28 Aug 2016

Night Microphysics RGB

You can determine the thickness of stratus and convective clouds in the night microphysics RGB. The greener or lighter blue-grey the stratus clouds, the thicker they are. In the image below, the low clouds over Angola are thicker to the east, and thinner to the west where the purple is showing through the blue-grey.

EUMETSAT night microphysics RGB over Africa, 0000 UTC 24 Aug 2016

Convective clouds are red. The more saturated the red, the thicker they are.

Cirrus clouds are thin and appear black in this product. But it's hard to determine their exact thickness due to the lack of texture in the black colouration.