The different kinds of clouds

1
The different kinds of clouds!

• This is directed towards the 6th grade Earth
  Science class.
• Amanda Rissley

2
What is a Cloud?

• A cloud is a visible aggregate of tiny water
  droplets and/or ice crystals suspended in the
  atmosphere and can exist in a variety of shapes
  and sizes.

3
High-level Clouds

• High-level clouds form above 20,000 feet. Since
  the temperatures are so cold at such high
  elevations, these clouds are primarily composed
  of ice crystals. High-level clouds are typically
  thin and white in appearance, but can appear in
  an array of colors when the sun is low on the
  horizon.

4
Cirrus Clouds

• The most common form of high-level clouds are
  thin and often wispy cirrus clouds. Typically
  found at heights greater than 20,000 feet, cirrus
  clouds are composed of ice crystals that
  originate from the freezing of super cooled water
  droplets. Cirrus generally occur in fair weather
  and point in the direction of air movement at
  their elevation.

5
Cirrostratus Clouds

• Cirrostratus are sheet-like, high-level clouds
  composed of ice crystals. Though cirrostratus can
  cover the entire sky and be up to several
  thousand feet thick, they are relatively
  transparent, as the sun or the moon can easily be
  seen through them. Sometimes the only indication
  of their presence is given by an observed halo
  around the sun or moon. Halos result from the
  refraction of light by the cloud's ice crystals.

6
Mid-level Clouds

• The bases of mid-level clouds typically appear
  between 6,500 to 20,000 feet. Because of their
  lower altitudes, they are composed primarily of
  water droplets, however, they can also be
  composed of ice crystals when temperatures are
  cold enough.

7
Altocumulus Clouds

• Altocumulus may appear as parallel bands or
  rounded masses. Typically a portion of an
  altocumulus cloud is shaded, a characteristic
  which makes them distinguishable from the
  high-level cirrocumulus. Altocumulus clouds
  usually form by convection in an unstable layer
  aloft, which may result from the gradual lifting
  of air in advance of a cold front.

8
Low-level Clouds

• Low clouds are of mostly composed of water
  droplets since their bases generally lie below
  6,500 feet. However, when temperatures are cold
  enough, these clouds may also contain ice
  particles and snow

9
Nimbostratus Clouds

• Nimbostratus are dark, low-level clouds
  accompanied by light to moderately falling
  precipitation. Low clouds are primarily composed
  of water droplets since their bases generally lie
  below 6,500 feet. However, when temperatures are
  cold enough, these clouds may also contain ice
  particles and snow.

10
Stratocumulus Clouds

• Stratocumulus clouds generally appear as a low,
  lumpy layer of clouds that is sometimes
  accompanied by weak intensity precipitation.
  Stratocumulus vary in color from dark gray to
  light gray and may appear as rounded masses,
  rolls, etc., with breaks of clear sky in between.

11
Vertically Developed Clouds

• Generated most commonly through either thermal
  convection or frontal lifting, these clouds can
  grow to heights in excess of 39,000 feet,
  releasing incredible amounts of energy through
  the condensation of water vapor within the cloud
  itself.

12
Fair Weather Cumulus Clouds

• Fair weather cumulus have the appearance of
  floating cotton and have a lifetime of 5-40
  minutes. Known for their flat bases and distinct
  outlines, fair weather cumulus exhibit only
  slight vertical growth, with the cloud tops
  designating the limit of the rising air. Given
  suitable conditions, however, harmless fair
  weather cumulus can later develop into towering
  cumulonimbus clouds associated with powerful
  thunderstorms.

13
Cumulonimbus Clouds

• Cumulonimbus clouds are much larger and more
  vertically developed than fair weather cumulus.
  They can exist as individual towers or form a
  line of towers called a squall line. Fueled by
  vigorous convective updrafts, the tops of
  cumulonimbus clouds can easily reach 39,000 feet
  or higher.

14
Other Cloud Types

• These are a collection of miscellaneous cloud
  types which do not fit into the previous four
  groups.

15
Contrail Clouds

• A contrail, also known as a condensation trail,
  is a cirrus-like trail of condensed water vapor
  often resembling the tail of a kite. Contrails
  are produced at high altitudes where extremely
  cold temperatures freeze water droplets in a
  matter of seconds before they can evaporate.

16
Billow Clouds

• Billow clouds are created from instability
  associated with air flows having marked vertical
  shear and weak thermal stratification. The common
  name for this instability is Kelvin-Helmholtz
  instability. These instabilities are often
  visualized as a row of horizontal eddies aligned
  within this layer of vertical shear.

17
Mammatus Clouds

• Mammatus are pouch-like cloud structures and a
  rare example of clouds in sinking air. Sometimes
  very ominous in appearance, mammatus clouds are
  harmless and do not mean that a tornado is about
  to form a commonly held misconception. In fact,
  mammatus are usually seen after the worst of a
  thunderstorm has passed.

18
Orographic Clouds

• Orographic clouds are clouds that develop in
  response to the forced lifting of air by the
  earth's topography (mountains for example).

19
Pileus Clouds

• Pileus is a smooth cloud found attached to either
  a mountain top or growing cumulus tower.

20
Time for some work!

• Get out a piece of paper and a pencil and write
  down your answers. Or you can click on the button
  to print out a work sheet.

21
What are these clouds?
1
2
3
5
4
22
What about these?
8
6
7
10
11
9
23
Time for the answers!

• 1. Altocumulus
• 2. Billow
• 3. Cirrustratus
• 4. Cirrus
• 5. Contrail
• 6. Nimbostratus

7. Cumulonimbus 8. Orographic 9. Pileus 10.
Mammatus 11. Stratocumulus
24
References

• http//ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/c
  ldtyp/home.rxml

25
Work Sheet