Geoscience Reference
In-Depth Information
Vapor pressure near curved surfaces
: saturated vapor pressure above curved
surfaces is higher because water molecules can escape more readily from
them so condensation is easier onto droplets with larger radius.
●
Droplet concentration
: cloud droplet density is about 1000 times less than
aerosol density (
●
10
12
m
−3
) because condensation is easier
onto larger radii aerosols that are much less common (see last two points).
∼
10
9
m
−3
versus
∼
How do clouds work?
: smaller cloud particles with lower terminal velocity
are swept upward or hang almost stationary in the atmospheric uplift in
clouds until some particles grow large enough to fall quickly through the
cloud, gathering water from smaller particles as they do so. These leave the
cloud and some may be big enough to reach the ground before evaporating.
●
Cloud types
: three types of cloud are distinguished by their temperature,
cold clouds (
●
<
-40°C), mixed clouds (-40°C to 0°C) and warm clouds (
>
0°C).
Cloud formation
: three important cloud formation mechanisms described
in the text are
Thermal convection
, the
Froehn effect
, and
Extratropical fronts
and cyclones
.
●
Cloud genera
:
cumulus
means 'heaped,
stratus
means 'layered, and
cirrus
means 'fibrous, with
nimbus
indicating rain clouds used as a qualifier, and
alto
and
cirro
respectively used as a prefix to indicate 'medium' and 'high.
●
