UIAA-Handbook_FLIP__

A.2.13
How do you assess changing weather conditions
in the field?
The arrival of bad weather always alters the sky’s appearance. Recognizing the first
signs of a change in the weather often enables you to take shelter before the arrival
of a disturbance or thunderstorm.
Cirrus, filament-like clouds, indicate
an increase in humidity at altitude. They
may indicate a potential disturbance.
A saucer-shaped cloud forms over the
high peaks. These altocumulus lenticular
clouds indicate strong winds at
altitude. If these clouds extend to other
peaks, the weather will likely deteriorate
within hours.
If cirrus clouds multiply and form a veil
covering the sun or the moon, the disturbance
is confirmed.
Cirrus clouds followed by a wall of
clouds often indicate the rapid arrival of
a cold front, with a violent disturbance
accompanied by a sharp drop in temperature
likely. Take immediate shelter.
Small cumulus in a blue sky early in
the day may signal potential afternoon
thunderstorms.
Cumulonimbus clouds indicate an
imminent thunderstorm.
Do not use withou
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