Turbulence remains an important unsolved problem of
classical physics. It is important in pipe flow, ship
design, aeronautics and, of course, in meteorology.
Many things around us show the results of turbulence,
and we rely on it to perform many useful duties, such
as dissipating pollution and evaporating water.
Turbulence is invisible, so it is often overlooked,
even when most active.
http://www.du.edu/~etuttle/weather/turbul.htm
Atmospheric turbulence is small-scale, irregular air
motions characterized by winds that vary in speed and
direction. Turbulence is important because it mixes and
churns the atmosphere and causes water vapour, smoke,
and other substances, as well as energy, to become
distributed both vertically and horizontally.
Atmospheric turbulence near the Earth's surface differs
from that at higher levels. At low levels (within a few
hundred metres of the surface), turbulence has a marked
diurnal variation under partly cloudy and sunny skies,
reaching a maximum about midday. This occurs because,
when solar radiation heats the surface, the air above
it becomes warmer and more buoyant, and cooler, denser
air descends to displace it. The resulting vertical
movement of air, together with flow disturbances around
surface obstacles, makes low-level winds extremely
irregular. At night the surface cools rapidly, chilling
the air near the ground; when that air becomes cooler
than the air above it, a stable temperature inversion
is created, and wind speed and gustiness both decrease
sharply. When the sky is overcast, low-level air
temperatures vary much less between day and night, and
turbulence remains nearly constant.
At altitudes of several thousand metres or more,
frictional effects of surface topography on the wind
are greatly reduced, and the small-scale turbulence
characteristic of the lower atmosphere is absent.
Although upper-level winds are usually relatively
regular, they sometimes become turbulent enough to
affect aviation.
http://www.britannica.com/eb/article-9010124/atmospheric-turbulence
In ground based telescopes, this diffraction-limited
resolution is never reached. Ground-based telescopes
must look through miles of the Earth's atmosphere.
Turbulent fluctuations in the wind velocities in the
upper atmosphere mix layers of differing temperatures,
densities and water vapor content. Thus the index of
refraction of each level of the atmosphere fluctuates.
The wavefront incident on the telescope has spatial and
temporal variations in phase and amplitude due to these
fluctuations in the index of refraction along the
optical path.
Turbulence is a non-linear process, and so the
equations governing it are non-linear. In 1941,
Kolmogorov attempted to model turbulence in the
atmosphere using a statistical approach. The
Kolomogorov theory of turbulence is based on the
assumption that wind velocity fluctuations are
approximately locally homogeneous and isotropic random
fields for scales less than the largest wind eddies.
http://www.pha.jhu.edu/~jlotz/aoptics/node3.html
2007-04-04 03:37:57
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answer #1
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answered by Anonymous
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Fluctuating motion of air indicates the presence of turbulance in the atmosphere.The atmosphere becomes turbulent when there is mechanical obstruction to the flow of air or there is a marked convection in the atmosphere.The former is called mechanical turbulence while the latter is called thermal turbulence.
When the flow of air is obstructed by tall buildings or small hills,rotating parcels of air known as eddies are created(this is called mechanical turbulence) which manifest itself in the form of gusts and lulls near the surface.
Thermal turbulence are caused by the intense isolational heating of air layers near the surface resulting in the formation convective currents which rise above and produce fluctuations in the air flow, in the form of gusts and lulls.
Diurnal variation of wind is caused by these turbulences only.Sea-breeze and land_breeze are well known examples of this diurnal variation of wind near the coastal places.
Another turbulence called clear air tubulence occurs at high altitudes mainly in the high troposphere and low stratosphere especially in the vicinity of jet streams.Large horizontal and vertical wind shear are responsible for this.Orographic effects may also be a contributory factor.
2007-04-04 14:31:38
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answer #2
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answered by Arasan 7
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Hey have you ever watched the movie, 'Hunt for the Red October'? The guy on the plane gives a great description of turbulence. And not to mention it is a GREAT movie!!
2007-04-04 09:44:07
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answer #3
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answered by cbmultiplechoice 5
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I have the best answer for your question "What is the turbalance of atmosphere?". Please click the link below to check my answer:
2007-04-04 09:42:22
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answer #4
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answered by Jessica R 1
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