Transcript Types of Clouds and formation

Clouds
The Recipe
• Clouds need three things to form
– Moisture
– Cooling air to it’s Dew Point (condensation)
– Condensation Nuclei (dust, smoke)
How do we get to the Dew Point
• The easiest way to bring an air masses
temperature to it’s dew point is to move air
to a higher altitude
Cool
As the moist air rises it’s temperature
decreases and the water vapour begins
to condense
Warm
Moist Air
• The drier air is the
farther it has to
climb to reach it’s
dew point
• At higher altitudes
the temperatures
are much colder
and below freezing
Moist Air
Dry Air
• Moist air has more
water vapour and
will become
saturated at a
warmer temperature
• As a result clouds
will form at lower
altitudes out of
water droplets
Moist Air
• When the Dew point
is below freezing
this means that
when the water
vapour condense it
will actually freeze
into ice crystals
• This usually
happens at very
high altitudes in dry
conditions
Moist Air
Cloud types
• Clouds can be classified in three different
ways
– Shape
– Altitude
– Is there precipitation?
Cloud Shape
• Cumulus
– Puffy
• Stratus
– Shapeless
– fog
• Cirrus
– Dry conditions
– Ice crystals
Cloud Height
• Up to 2000 m
– Just use cloud shape name
• 2000 – 6000 m
– Use prefix “alto” with the shape
• 6000 m and above
– Use prefix “cirro-” or suffix “-cirrus” with cloud
shape
– Example – altostratus or cirrostratus
Precipitation
• Precipitation
– Use prefix “nimbo-” or suffix “nimbus” with the
shape
– Example - cumulonimbus
Precipitation
• The average drop is just 0.02 mm across
in a cloud (too small to fall)
• By the time it hits the ground the average
drop is 2 mm across
• So how does it grow?
Growing by Coalesce
• As the raindrop falls
in the cloud it collides
with other drops and
begins to grow
• Wind will continue to
circulate the drop until
it becomes to heavy
and falls to the
ground as
precipitation