Outline

1
Outline
- what is a cloud?
- cloud classifications
- clouds and precipitation
2
Introduction

• Previously,
• We learned that when air is ___________________
• We also discussed what happens once the
  temperature cools. We expect ____________________
  ________________
• Today,
• We want to discuss what forms these clouds take
• Classify cloud formations
• Discuss characteristics that allow us to identify
  different types of clouds

3
Cloud Type by Form

• Clouds
• Clouds ___________________________________________
  ______________

• Clouds can be classified by some simple criteria
  that also provides information on the atmospheric
  conditions
• One form of classification is based on
  _________________________

Cirrus ________________
Stratus ________________ _______________________
Cumulus ___________________________
4
Cloud Type by Altitude-01

• Can also classify them based on their
  ______________
• Cirro
• Alto
• Strato
• Fog

Cirro _______________________________
Cirrocumulus high, puffy clouds
Cirrus high, wispy clouds
5
Cloud Type by Altitude-02
Alto ______________________________
Altocumulus individual or rolls of clouds
Altostratus thin, layered clouds
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Cloud Type by Altitude-03
Strato ____________________
Stratocumulus groups of dense, puffy clouds
Stratus Dense, uniform gray layers
7
Cloud Type by Altitude-04
Fog ________________________ Radiation fog forms
at night when cold ground cools the air above it
(in valleys) Advection fog forms when warm,
moist air moves over colder surface and cools (in
coastal areas)
8
Cloud Type by Rain

• Finally, we can classify them based on the
  _____________________
• _________________ any cloud that rains

Cumulonimbus vertical clouds that produce rain
Nimbostratus low, flat clouds that drizzle
9
Thunderstorms

• Thunderstorms ____________________________
• _________________________________________
• Actually composed of many individual circulation
  cells
• Updraft region is where the upward motion is
  intense and where the rain typically falls
• Downdraft region is associated with downward
  motion which can also be intense -gt leads to
  downbursts
• Cells are typically 10-20km across and
  circulation within them occurs over 20 minutes or
  so, i.e. new cells can form in 20 minutes
• ________________ this is when an ice particle is
  continuously cycled through the convection cell
  before becoming heavy enough to fall out
• _______________________ as water is moved within
  the cell, it develops a fictional charge the
  discharge occurs through a spark, i.e. lightening

10

• How far away is lightning?
• The precise speed of sound through air was
  determined in 1832 by two Dutch scientists.
  Their measurements where later corrected to
  _________ (1090 feet) per second at an air
  temperature of zero degrees Celsius.
• You can use their discovery to calculate how near
  you are to a lightning strike. Simply count the
  number of seconds between the lightnings flash
  and the thunders boom. _________________________
  ________________________________________ (or one
  mile for every five seconds)

11
Clouds and Precipitation-01

• Rain (or any precipitation)
• Requires
• _______________
• Presence of condensation nuclei -gt
  ___________________________________
• Condensation does not necessarily mean rainfall
  ___________________________
• In order to form precipitation, the drops must be
  large enough to fall against the upward motion of
  the air
• Cloud droplets are typically 50-100 micro-meters
  in diameter
• In contrast, rain drops are typically 500
  micro-meters before they begin to fall (drizzle)
• At 1000-2000 micro-meters, they are considered
  rain drops

12
Clouds and Precipitation-02

• There are also other forms of precipitation
• Snow - ___________________________________________
  __________
• Sleet - __________________________________________
  ___________
• Hail - __________________________________________
  ____________
• Note that precipitation does not necessarily fall
  straight to the ground - it might start to fall
  then get caught in an updraft and cycle through
  during this process more aggregation occurs and
  we get very large rain or hail falling out (i.e.
  golf-ball size hail)