Kiker Module3 Characteristics of the Atmosphere.pdf - AOM...

AOM 4643
Principles and Issues in
Environmental Hydrology
Composition/Characteristics of the
Atmosphere

Agenda
• A really atmospheric overview…
• Spatial Distributions of temperature,
pressure and precipitation – Why?

Composition/Characteristics of
the Atmosphere
• 80% Nitrogen, 20% Oxygen- treated as a perfect gas
• Lower atmosphere extends up to  50 km.
• Lower atmosphere most active part of atmosphere
where most of the mass and energy transfer (leading
to earth’s weather patterns) occurs. It is divided into
two parts distinguished by their temperature
distribution -- the troposphere and the stratosphere.
• Upper atmosphere doesn’t play much of a role in the
determination of weather.

Characteristics of the
Atmosphere
Altitude (km)
Temperature  C
-80 -60 -40 -20 0 20
sharp change in temp. and
pressure produce Jet
Streams
50 km
lower atmosphere
Stratopause
Stratosphere
upper
atmosphere
Mesopause
Mesosphere
100 km
Thermosphere
8 - 16 km
Tropopause
Troposphere poles
equator

Characteristics of the Troposphere
• Variable thickness (8 km poles, 16 km equator).
• Decreasing temperature with elevation (linear).
• Well defined pressure gradients (max. pressure at bottom).
non-linear
• Well defined distribution of moisture and suspended
particles (max. at bottom)
•Sharp air velocity gradient. At earth’s surface velocity is
zero (no-slip condition) and velocity increases over 2700 m
thick boundary layer according to a logarithmic velocity
profile
P
Elev
T
Elev
Z
o
– roughness height – depends
on conditions at earth’s surface
Velocity
Elev
Z
o
Driving
forces for
energy
transport in
lower
atmosphere