|
|
|
|
Cloud Primer
Wed May 19, 2004
Listen in RealAudio 
A Cloud Primer, next on The Weather Notebook.
By 2000 years ago, the nighttime constellations were fairly well established, but the
naming of clouds was not really pinned down until the early 1800s. The man who is
most credited with classifying the clouds was named Luke Howard. Hi, I’m Bryan
Yeaton, and this is The Weather Notebook.
Howard’s nomenclature became more easily accepted than competing systems
because it described the clouds as they appeared from the ground. There were four
basic types. The puffy, fair weather clouds are called "cumulus," a word that means,
"heaping," like a pile of mashed potatoes. The blanket clouds that can cover the whole
sky are "stratus," or layered. Wispy "cirrus" clouds are derived from "curl of hair," and
they do sometimes seem to appear as windblown hair, or as they are sometimes
called, "mare’s tails." The last type, "nimbus," meant that the cloud would bring heavy
rain.
Howard intended that these four terms could be combined to describe many
variations. For example, a puffy, heaping cloud that brings a lot of rain is called
cumulonimbus—our thunderstorm cloud.
Howard’s classification system was expanded by Abercromby and Hildebrandsson in
1887, and this is the system we still use today. One of the things they did was to create
10 subclasses within four groups, based on height. High clouds, which in the
Temperate Zone occur between 16 and 43,000 feet. Middle clouds cover from 6,500 to
23,000 feet, and the lower clouds stretch from about 6,500 feet right down to the
ground. In fact, fog is just a cloud with its base on the ground. There is also a category
for clouds with vertical development, which includes the cumulus and cumulonimbus.
To connect to cloud charts, go to our website: www.weathernotebook.org.
We are supported by the National Science Foundation and Subaru of America.
Today's Links
Cloud Quiz
http://www.mountwashington.org/discovery/quiz/clouds/
NOAA Photos of Various Cloud Types
http://www.photolib.noaa.gov/historic/nws/nwind1.htm
|
|
