Cloud Types

[gumm]

Hi guys,

I had an interesting (at least to me) discussion with a friend of mine around the names of different cloud types, i.e. cumulus, stratus, cirrus etc.
He made a comment that I find hard to believe, claiming that the prefix "nimbo" (as is nimbostratus) or the postfix "nimbus" (as in Cumulonimbus) is *only* used when actual precipitation is occuring.

The reason I find this hard to believe, is that the implication is that the characteristic anvil shaped "cumulonimbus" cloud, is in fact called something else unless one can confirm that it is in fact precipitating.

What adds confusion is that sites like Wikipedia and others are ambiguous on the topic, either talking about "precipitation bearing" clouds, or making statements like: "precipitating clouds are called nimbus" - which in my view does not preclude anything else - including non-precipitating clouds from carrying the name nimbus.

Any (real or armchair) meteorologists care to enlighten me please

Regards
Jan

[Budgie]

I was a Met Observer for 7 years and attended a weeks course at the Met Office collage in Reading to train and that wasn't part of anything I used or was told.
The description "rain bearing cloud" is the correct one IMHO as you can't always tell that there's precipitation falling from the base of a cloud unless you're directly under or very close to it.

The "official" line: http://www.metoffice.gov.uk/publications/clouds/

[AndrewNZ]

Hi guys
I was a meteorological technician/observer with the New Zealand Meteorological Service back in the eighties before they replaced us all with automatic stations. Based on my training and experience (and memory) gumm's friend is incorrect. Nimbostratus or Cumulonimbus may be reported as being present at a time when they are not producting precipitation, however it is hightly likely that it will occur before or after that time. There are other things besides precipition which characterise these clouds. For example when a towering cumulus reaches the stratosphere and an anvil is produced it becomes a cumulonimbus regardless. It will have a great vertical extent and a darkened base. Also if you hear thunder and/or see lightning then the cloud automatically graduates to a Cumulonimbus. I will have to try and did out my old met school study notes to clarify it though. We had this huge manual which covered every conceiveable question regarding weather observing.

[gumm]

Hi Andrew and Budgie,

Thanks for clearing that up for me... and excuse the bad pun

Kind regards
Gumm