Unidentified Clouds

[welshrich]

July Clouds in the Swansea Valley of South Wales. Some and grey, some white. I am just beginning to learn clouds and was wondering if anyone could tell me what they are and why some are grey and some white.


Canon 350D
Focal Length 18mm
ISO Speed 100
Aperture f/10
Shutter 1/250

[welshrich]

After some research I guess they are cumulus but I am still not sure why some are white and some are grey.

[Alan]

Maybe it's that the greyer they are, the more water they hold! Density or something.

[Mr Mag00]

Maybe it's that the greyer they are, the more water they hold! Density or something.

correct!

[henrya]

The grey bits are the bits in shadow!

henrya

[FungiJohn]

Small white cumulus clouds (fair weather) clouds do not have much water in them, so there is not much to stop sunlight from passing through them and making them look white.

Dark grey rain clouds have lots of water in them and block or absorb the sunlight that falls on them. They also tend to cover the sky, so there is very little chance for sunlight to be reflected off the sides of them.

Hope it helps

[Alan]

Originally Posted by FungiJohn

Small white cumulus clouds (fair weather) clouds do not have much water in them, so there is not much to stop sunlight from passing through them and making them look white.

Dark grey rain clouds have lots of water in them and block or absorb the sunlight that falls on them. They also tend to cover the sky, so there is very little chance for sunlight to be reflected off the sides of them.

Hope it helps

Head in the clouds again John

[FungiJohn]

Originally Posted by Alan

Head in the clouds again John

Wish it was Alan. It's wading through a very boring coldfusion technical paper right now .... with a few WAB breaks in between

[welshrich]

Thanks Fungi John - I have since found this explanation which is also good.

Clouds are quite reflective. If you fly over clouds and look down on them (or view clouds on visible satellite images), you will see just how white they can be. When viewed from Earth, the tops and sides of many clouds (cumulus especially) are very white. The whiteness is a measure of how much visible light (from all the colors of the spectrum) is being reflected.

The bottoms (and sometimes the sides) of clouds (most noticeable in cumulus type clouds) are varying shades of gray. This is because of shadowing. The cloud itself or clouds above it or to its side) block sunlight from reaching some parts of the cloud. The thicker the cloud (or the more cloud layers present), the more shadowing, and hence the darker the cloud. If the cloud bottom is almost black, the cloud is most likely a cumulonimbus or thunderstorm cloud.