On Jul 2, 3:37*pm, "Togless" wrote:
"Tudor Hughes" wrote:
On Jul 2, 11:59 am, "Togless" wrote:
Looking north from my house here in Portsmouth I can see large grey
clouds
looming up rather quickly, and on the satellite photos it has all
developed
just in the last 2 hours or so - what is that called, when (presumably)
the
heat of the sun makes the sky go from clear blue to masses of cloud in
just
a couple of hours? *Anyway, I'm hoping that an onshore breeze will keep
it
away from us here on the coast. *Sometimes being on the coast works in
our
favour, and sometimes not (sea mist etc).

John.

* * *It's convection over the heated land. *The air will cool as it
rises and will form cloud when it reaches saturation. *Today it won't
rise very far because there is warmer air aloft so the cloud spreads
out. *We have similar cloud here.

Thanks Tudor - I knew about the first part, but hadn't appreciated the
second. *What do you use to determine that there is 'warmer air aloft', if
you don't mind me asking? *Presumably in different circumstances you would
get large high cumulus clouds and the risk of intense precipitation - is
that right?- Hide quoted text -

- Show quoted text -

If the inversion or "lid" (shown very well in Graham's link)
were not there the surrounding air would be colder and the rising air
would remain buoyant to a much greater height and would form large
cumulus or cumulonimbus clouds. These could certainly give you
intense precipitation and even thunder.

Tudor Hughes, Warlingham, Surrey