Hi all,

I was just outside and it's a perfect summer day ... warm with a cool breeze, bright and sunny with blue skies from horizon to horizon.

Except for one small cloud.

No other clouds anywhere around except for this solitary individual.



Sure, it's just a cloud and no big deal ... except that it got me thinking that for something as commonplace as a cloud that each of us sees almost every day of our lives ... that personally, I really know very little about them from a meteorological point of view..

As you can see from the pic above, the cloud has a fairly well defined boundary. Yes, I know that if we got up close to the cloud that the boundary would become more and more fuzzy but from a distance, there's obviously two distinct regions separated by a boundary ... the blue sky region surrounding the cloud and the interior of the cloud.

Now in my mind, that's an obvious indicator that these 2 distinct regions must have very different properties and conditions from each other. It then occurs to me to consider that at some point in time, the cloud didn't exist and it was basically just blue skies but then something had to change or alter, resulting in the formation of the cloud.

As our resident weather expert, this simple question of mine is probably going to be easily answered by OzWeatherman but I'm just curious as to what set of circumstances could trigger the formation of just a single cloud ... why does atmospheric moisture start to condense at a particular spot and then continue condensing ... finally to stop at what becomes the clouds edge boundary ? Why doesn't the condensation just continue ? What process or conditions causes the condensation to halt ?

Simple questions I'm sure ... but one's I've never really thought about until now.
Sometimes we simply take our world and it's wonders for granted

I don't know, but I've seen the exact same thing. It happened in the summer, about 10 km from the coast, at the same time in the afternoon. One little cloud in a clear sky, then after a few minutes it disappeared.

The sky isn't a constant medium, for example a layer of low humidity can be sandwiched between layers of high humidity etc.

So the small cloud you saw just happened to be in a right area of ideal conditions for clouds to form. As it travels along, the conditions return to the same as the surrounding areas and it disappears.


I think that covers the simple part!

[edit on 2/1/10 by Chadwickus]

I don't have one.
But I took two photos a few seconds apart and a similar cloud
did not appear on the second photo.
I always thought it was the film.
ED:
A similar 'cloud', do you have rays going down to earth?


I have a Rex Heflin ring:



[edit on 1/2/2010 by TeslaandLyne]

I think Chadwickus answered it pretty well

You can get pockets of air where the air cools significantly enough for cloud to form momentarily, only to dissapear as soon as it appeared. This happens quite frequently over water bodies through evaporation, though its not restrcited to those areas.

Its important to note that the atmosphere is not a constant. Just because cloud forms in one spot, does not mean that cloud will form in another area.

Hope that helps a little