MadSci Network: Earth Sciences

Re: What is the avg. (and max.) wind speed in the stratosphere?

Date: Sat Sep 25 19:04:09 1999
Posted By: Michael L. Roginsky, Staff, Avionics, Honeywell Defense Avionics
Area of science: Earth Sciences
ID: 936732246.Es

Hi John: Very excellent project you have in mind. My first question is how 
are you going to have your unmanned aircraft fly through a 
less-than-friendly (weather beaten) 60,000 ft of atmosphere before you can 
level off at 70,000 ft? My second question is how are you going to maintain 
a parked orbit once the UAV gets there? Please do not let my engineering 
bias stop you from getting there. Let me hear of your success! 

Since I lived with airplanes from my early years, I am thrilled to give you 
the information you asked. Bear in mind, these parameters are based on 
ideal conditions. Weather plays an important part in the atmospheric 
conditions. Some thunderheads may soar as high as 60,000 ft with violent 
vertical wind shears that can easily destroy the most robust aircraft. So, 
please take this information with a  "grain-of-salt".  On the basis of 
atmospheric temperature, scientists distinguish five layers:

1. Troposphere extends up to 36,000 ft above the Earth's surface. It is the 
region closest to the Earth's surface and where weather most often occurs. 
It is characterized by a decrease in temperature with increasing altitude. 
Winds in this layer move mostly in a vertical motion as the result of 
convection heating of the earth's surface by the sun. However the 
prevailing hemispherical winds, jet streams, also are present. They move 
mostly in a horizontal direction, west to east in the Northern Hemisphere, 
and East to West in the Southern Hemisphere. At 25,000 to 35,000 feet in 
altitude these winds may reach 200 miles per hour along narrow corridors. 
The temperature of the troposphere falls at high altitudes. At 36,000 feet 
the temperature averages -56 C.

2. Stratosphere extends up to 131,000 above the Earth. The average 
temperature remains steady at -56 C up to an altitude of 82,000 feet. 
Above this altitude, the temperature rises. Jet streams there move in a 
horizontal motion and at lower speeds, perhaps 100 miles per hour. A 
significant feature of the stratosphere is the ozone layer, which is 
located between 52,500 ft and 105,000 ft above the Earth. This layer 
protects the Earth by absorbing harmful ultraviolet radiation from the sun.

3. Mesosphere - up to 150,000 ft above the Earth - is characterized by a 
rapid decrease in temperature with increasing altitude. Noctilucent clouds, 
(water vapor or meteor dust) that shine at night, are a distinguishable 
feature of this layer. 

4. Thermosphere extends up to 300 miles (480 kilometers) and is 
characterized by a rapid rise in temperature with increasing altitude. The 
phenomenon of airglow, luminescence due to re-radiation of sunlight by 
heated atmospheric particles, originates in this layer. Auroras are a 
spectacular feature of this layer. 

5. Exosphere extends beyond the thermosphere. The density of the air is so 
low in this layer that the concept of temperature loses its customary 
meaning. Ultraviolet rays fill the exosphere, and faint glows called 
zodiacal light that are due to sunlight reflected from particles of 
meteoric dust originate in this layer. 

Cloud formations:

The names of the 10 genera are derived from combinations of Howard's three 
classifications of clouds: cirrus, stratus, and cumulus, with the addition 
of the word alto for high clouds and nimbus for rain clouds.

High clouds have a normal range in altitude from 16,500 to 45,000 feet and 
include (from highest to lowest): cirrus, cirrocumulus, and cirrostratus. A 
cirrus cloud appears in delicate, feather-like detached bands, sometimes in 
tufts, and is usually white with no shading. Cirrocumulus clouds look like 
very small round balls or flakes.
Sometimes cirrocumulus clouds form the pattern of the buttermilk or 
mackerel sky. Cirrostratus clouds sometimes form tangled webs or thin 
whitish sheets. When cirrostratus clouds cover the sky, a large ring or 
halo is sometimes seen around the sun or moon. This is caused by the 
natural bending of rays of sunlight or moonlight as they pass through the 
ice particles. 

Note that because of the unique temperature/pressure distribution of our 
atmosphere, water does not escape into space.
Good luck, MAD.SCI Micro.

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