J. Mc Laughlin wrote:
Dear Dave (no call):

If you wish to get down to details, the standard for most of such
calculations can be found in ANSI/TIA standard 222G. Put 222G and wind - or
the like - into Google. A copy of the standard itself is expensive.
Earlier versions were quite inexpensive.

For low towers and antennas, especially in an urban or built-up area,
simple is usually good enough.

Regards, Mac N8TT

Depends on what your regulatory environment is, too...

A 50 foot tower out in the middle of a 160 acre field will typically
require less analysis to meet the local rules than a 100 foot tower on
5000 ft suburban lot.