Hello everybody!


This is a question I've been meaning to ask for a very, very long time, thought I'd ask it now...

Is it possible to determine (at least estimate) the height (in metres/kilometres and/or feet/miles) of cumulonimbus storm clouds, and if so, how?

Any thoughts and comments? Thanks

Well what I do to measure the height of them by looking at the local and most up to dated soundings. Look at the cap layer height, that is where the uppermost height of the cloud will grow.

Look at this example:



This chart appears to have the maximum height of 12.3km. However, slight concern that not all storm clouds will be having at 12.3km since that is the maximum below the stable layer (cap).

This is one of the method we can determine, but Im sure other posters in this forums would have different method as well.

Except perhaps for overshooting tops. It would be interesting to see a sounding of that scenario. I've seen photographs of storm clouds with double anvils and a total height of around 60000 feet, from memory.

And the other thing, is that when you spot a Cb and do have a sounding from perhaps a few hours earlier, that won't necessarily be the situation when the cloud is spotted.

I think a lot of experience would come from estimating cloud heights in general, but it's really only educated guessing without soundings or some other scientific method.

Rule of thumb used by glider pilots =Temp[ C ] minus Dew Point x 400 = cloud base in feet.

And a web site calculator; http://www.csgnetwork.com/cloudaltcalc.html

Another method I use all the time that does not need temperatures but does need lots of experience is to take a look at our local Grampian mountains which I know the height of the peaks nearest us and see how far above the peaks those clouds bases are or the multiples of the peaks heights that the cloud bases are at.

And if you aren't sure if the clouds you are looking at are actually over or close to the peaks then the cloud shadows and their location on the ranges or the peaks can often tell you where those clouds are located.

For cloud top heights, the vertical fist at full arms length and an estimate of the distance can give a very rough approximation of a Cu-nim's top's height.
This does require you to have some experience as it is all guesstimation and experience and practice..

I use this to guesstimate to measure the height of lenticular wave clouds over the Grampians which occur in about the same place most of the time.
The distance is known at approximately 80 kms to Mt William and the fist width measurement estimate was developed by using con trails from the Melbourne / Adelaide jets which fly a route roughly over the Grampians at roughly 30,000 feet.

For a further explanation of this method and some interesting variations on the method;

Measuring Angle and Distance with your Thumb

How do you tell exactly where the cap is? I thought stability resulted from the air parcel temperature being below the temperature plotted by the red line, but in this chart the grey line crosses the red temperature line several times. So how far apart do they have to be in order for you to have a true cap? And how do you determine the upward velocity of the air parcel? I suppose the magnitude of that would influence how big a cap it can break through?

You can see the change in line direction at the height. Notice the turning up where the line becomes to the right.

Look at 200mb level in above chart.

Without been an expert myself Mathew, I fear you might be leading everyone down the wrong creek, again.

1. The inversion at 200mb is not the cap - that is the start of the tropopause.
2. The cap is a stable layer just above the surface. On your skew-t, this cap is around 900mb.
3. Cloud tops will typically be at the equilibrium level - where the brown line meets the red line in the graph above. Going by this sounding, there wouldn’t be any cumulonimbus clouds to start with and even if there was, there are several equilibrium levels, so what is the point of this graph?

Using this random sounding, cloud tops would be around 10km;



However overshooting tops etc could be higher. You would need satellite/radar to determine the cloud top exactly.

I'm no expert either, but as a minor addition my understanding is that if the grey line is between the dewpoint and the dry temperature then there is conditional instability, and the parcel has the potential to keep rising...until it crosses over the dewpoint trace.

Hey guys!

Thanks for the feetback, greatly appreciated. I'm no expert in this either, but this is a good chance to learn and hear what others have to say, cheers!

Thank you for the information, its really helpful.
greatly appreciated.