Kinematics

filercaliforniaMechanics

Nov 14, 2013 (3 years and 8 months ago)

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Land
-
Sea

Breezes

Figure 6.19

Land
-
Sea Breezes

Mountain
-
Valley

breezes

Figure 6.20

Chinook, Foehn, & Santa Ana
Winds



Winds that flow down the lee
side of mountain ranges

Hierarchy of Wind Systems


Global


ITCZ, Westerlies, and Rossby Waves


Last decades to centuries


Synoptic


Cyclones and Anticyclones, Troughs and Ridges,
Pressure cells


Last days to weeks


Mesoscale


Local winds


Last hours


Microscale


Dust devils


Last minutes

Kinematics

September 5, 2007

Kinematics


Means “to move” in Greek


Describes the motion of objects without
considering the masses or forces that
bring about that motion


Studies how the positions of things change
over time, measured in coordinates


Atmospheric Pressure and Motion


Differences in heating cause differences in
air density, which cause atmospheric
motion


In the midlatitudes, the surface air
temperature is due more to air movement
more than radiation received


Motion is a result of atmospheric pressure
differences

Geostrophic Wind


Winds in the upper atmosphere that flow
parallel to isobars


In the Northern Hemisphere, geostrophic
wind flows with low pressure to its left and
high pressure to its right

Geostrophic Wind

Gradient Wind


A wind that blows at a constant speed
parallel to curved isobars above the level
of frictional influence is a
gradient wind


An object accelerates when there is a
change in its speed or direction or both


Therefore the gradient wind blowing
around low
-
pressure is constantly
accelerating because its constantly
changing direction


centripetal
acceleration

Gradient Wind

Gradient Wind

Eddies


When the wind encounters a solid object,
a whirl of air


or eddy


forms on the
object’s downwind side


The size and shape of the eddy depends
on the size and shape of the obstacle


On a windy night, these produce tiny swirls
of air that act as pulses of compressed air
that reach you eardrum and produce a
howling sound

Turbulence


Eddies that form close to mountains and
beneath wave crests produce rotors


Rotors have violent vertical motion that produce
extreme turbulence

Turbulence


Sudden changes in wind speed or
direction (or both) abruptly produce wind
shear


Any irregular or disturbed flow in the
atmosphere that produces gusts and
eddies
-

Turbulence



Turbulent eddies are common near the jet
stream, where large wind speed shears exist

Microburst


A localized column of sinking air


Once it hits the ground, it spreads quickly
in all directions


Produces divergent winds at the surface


Damage similar to that of tornadoes


Tornadoes spiral inwards, microbursts
spiral outwards


Particularly troublesome for landing
aircraft

Clouds: The Basics