Mxsmanic wrote:
Milen Lazarov writes:
How are they ambiguous?

The heading in the table says "Distance from clouds," and the
distances are stated as (for example) "500 feet below." It's not
clear whether the aircraft must be 500 feet below the clouds, or the
clouds must be 500 feet below the aircraft. Clearly, this part of the
FARs was not written by a lawyer.

If it just said "distance", I'd agree. But it says "Distance from
clouds". Therefore the object in question is the airplane. If it had
said "Distance from airplane", then it would be talking about the
clouds.

As an aside, and I don't know if it's true or not (perhaps someone here
does)... but I recall reading that the reason it was 500' below and
1000' above, is because, in overcast conditions most planes descend at
500' per minute. Thus if a plane pops out of the bottom of a cloud,
you more or less have a minute to spot it. However, airliners ascend
at a higher rate, therefore you need more warning time if a plane pops
out of the top of a cloud. Or I suppose you could claim some
high-vs-low wing bias ;-)

Does anyone know the true reason behind the rule?

Kev