# Kinematics

Mechanics

Nov 14, 2013 (4 years and 4 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

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

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

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

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