Cloud Classifications

NWS -  By convention, clouds are vertically divided into three étages (levels); low, middle, and high. Each étage is defined by the range of levels at which each type of clouds typically appears. The types of clouds are...

Cirrus (Ci), Cirrocumulus (Cc), and Cirrostratus (Cs) are high level clouds. They are typically thin and white in appearance, but can appear in a magnificent array of colors when the sun is low on the horizon.

Altocumulus (Ac), Altostratus (As), and Nimbostratus (Ns) are mid-level clouds. They are composed primarily of water droplets, however, they can also be composed of ice crystals when temperatures are low enough.
Cumulus (Cu), Stratocumulus (Sc), Stratus (St), and Cumulonimbus (Cb) are low clouds composed of water droplets.

If you recall that the polar and subtropical jet streams are the dividing points between the polar, temperate, and tropical regions you will also notice the maximum height of the tropopause also decrease in each region as one moves from the equator to the poles.

Level Polar Region(PR), Temperate Region (TR), Tropical Region (TrR)

High Clouds - PR10,000-25,000 feet (3-8 km)  TR16,500-40,000 Feet (5-13 km)  TrR20,000-60,000 feet (6-18 km)
Middle Clouds PR 6,500-13,000 feet (2-4 km) TR 6,500-23,000 feet (2-7 km) TrR6,500-25,000 feet (2-8 km)
Low Clouds PRSurface 6,500 feet (0-2 km) TRSurface-6,500 feet (0-2 km) TrRSurface-6,500 feet (0-2 km)

  

Learning Lesson: Head in the Clouds

 OBJECTIVE:  The students will become better observers of the sky as they will see different types of clouds over several days.
 OVERVIEW:  Record the different types of clouds twice daily.
 TOTAL TIME:  5 minutes for each observation
 SUPPLIES:  Scissors, Brass fasteners

 
 
Background - Clouds are divided into four types (Cirro-form, Alto-form, Cumulo-form and Stratus) at three basic levels (low, middle and high) in the atmosphere. Many locations will experience all of these different types of clouds over a period of a week or so.
 
Discussion - Identifying clouds can be difficult at first. Have the students make their best effort in identifying the predominate cloud(s). Discuss any changes in the cloud type between the daytime observation at school and the evening observation at home. Discuss how the types of clouds change during the week, especially if a front passes your location. Discuss how we can look at the clouds to help forecast the weather.



Click here for the entire lesson:
http://www.srh.noaa.gov/srh/jetstream/synoptic/ll_clouds1.htm