chapter 7: clouds Flashcards
The result of condensation may be
fog, dew or clouds
The conditions of formation of condensation are:
- air must be saturated
- there are generally must be a surface on which the water vapor can condense.
- ascent of air
for any form of condensation the must be saturated. Saturation occurs when
the air is cooled below its dew point or
when sufficient water vapor is added to the air
there are generally must be a surface on which the water vapor can condense. This surface may be
an object at or near the ground where dew can form, or suspended particles in the atmosphere
This surface may be an object at or near the ground where dew can form, or suspended particles in the atmosphere (known as
condensation nuclei
define condensation nuclei
serve as surface on which water vapor condenses
fog forms near …………………….. and cloud at ………………….
the ground and clouds at a height
Condensation nuclei may be
dust, smoke and salt particles all of which are suspended in the atmosphere.
hygroscopics:
Particles that make the most effective cloud condensation nuclei
Particles that make the most effective cloud condensation nuclei are called hygroscopics which means
they are water-absorbent.
……………………………….. are also hygroscopics
Some familiar food items, such cracks and cereal
Some of the most common hygroscopic nuclei are
minute crystals of sulfate and nitrate compounds.
Hygroscopic nuclei are produced into the atmosphere by
burning (forest fires, automobiles and coal burning).
In addition salt from breaking ocean waves and
some particles found in ordinary dust can serve as cloud condensation nuclei
The important cloud-formation is the ascent of air. As a result,
, rising air expands and is cooled adiabatically. At a height called the lifting condensation level, the ascending parcel is cooled to its dew point temperature and further ascent causes condensation.
Clouds are one form of
condensation
Clouds are one form of condensation. They are best described as
visible aggregates of minute droplets of water or tiny crystals of ice.
Clouds are classified on the basic of two criteria
form and height
By form clouds are classified into:
- Cirrus: this type of cloud is formed at high altitudes, has a shape of thin white and often wispy. Cirrus clouds are composed of ice crystals that originate from the freezing of supercooled water droplets. Cirrus generally occur in fair weather and point in the direction of air movement at their elevation.
- Cumulus: clouds which they consist of globular individual cloud masses that sometimes look like pieces of floating cotton. The base of each cloud is often flat and may be only 1000 meters (3300 feet) above the ground. The top of the cloud has rounded towers and domes.
- Stratus: Stratus clouds are best described as sheets or layers (strata) that cover much or all of the sky.
By height clouds are classified into four basic types:
- High clouds.
- Middle clouds.
- Low clouds.
- Vertical development clouds
High clouds are the family of
cirriform clouds:
cirrus, cirrostratus and cirrocumulus clouds.
High clouds are normally have bases
above 6000m
Middle clouds have the prefix
alto
Middle clouds have the prefix alto as apart of name;
altostratus (As) and altocumulus (Ac)
Middle clouds base height
between 2000-6000 m
Low clouds are a family of
stratiform clouds;
stratus (St), stratocumulus (Sc) and nimbostratus (Ns)
Low clouds base height
below 2000 m
Nimbostratus clouds derive their name from
the Latin nimbus (rainy clouds) and stratus (to cover with a layer).
Nimbostratus is one of the
chief precipitation producers
Vertical development clouds associated with
unstable air
Unstable air forms
updrafts (convection)
Unstable air forms updrafts (convection), which produces
a type of clouds that extends vertically such as tower or dome
Unstable air forms updrafts (convection), which produces a type of clouds that extends vertically such as tower or dome. This type is a form of
cumulus (Cu) clouds (cumulus and cumulonimbus)
Cumulonimbus (Cb) is a cloud of
hazard weather such as thunderstorms, showers, turbulence
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