* Reading Assignments:

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Reading Assignments
All sections
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7. Hydrostatic Equilibrium
7.1 Effective gravity

• Radial gravitation
• by the planets mass
• Centrifugal acceleration due to
• rotation of the reference frame
• Anisotropic contributions

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7.2 Geopotential and Geopotential height
Geopotential
is the specific work performed against gravity to
displace a unit mass of air parcel from the sea
level to a height of Z.
Geopotential height
is nearly identical to geometric height, but has
different physical meaning.
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7.3 Hypsometric equation
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7.4 Stratification of environment
The environmental lapse rate
Layer of constant lapse rate
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Isothermal Layer
Layer of Homogeneous Density
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• One meteorology station is located at 250 m above
  
• the sea level. When it measures the pressure
  and
• temperature at 982 hPa and -12oC, another
  station
• has the pressure and temperature at 975 hPa
  and
• -14oC. What is the height of the this station
  above
• the sea level?

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2. One of the weather map is the 1000-500 mb
thickness map. The contour lines represent
the distance between these two pressure
surfaces. a) Use the hydrostatic equation
to derive a relationship between the
1000-500mb thickness and the average temperature
in the layer of 1000-500mb. b) The
1000-500 mb thickness is predicted to increase
from 5280m to 5460m at a given station.
Assuming that the lapse rate remains
constant, what change in surface temperature
would you predicted? (Assume the amount of
moisture in the air does not change.)
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3. A moist air parcel initially is at 500 m. Due
to the advection, the pressure of this air parcel
decreases 20 mb. Find if there is cloud forming
during this process. Assuming the process is
adiabatic the vapor pressure of the air parcel
is 8 mb at 500m and remains constant. The
vertical distribution of atmospheric pressure and
temperature are respectively, where P is in
mb, T in K, and z in m.
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7.5 Lagrangian Interpretation of stratification
Describing the atmospheric stratification in
terms of the behavior of individual air parcels
7.5.1 Adiabatic Stratification
For unsaturated moist air
The atmospheric potential temperature is
uniformly distributed with height,
The environmental lapse rate is constant and is
equal to the dry adiabatic rate,
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7.5.2 Diabatic Stratification
Air parcels interact with the environment through
the heat transfer when they move both
horizontally and vertically.
When the atmospheric temperature increases with
height,
the potential temperature increases with height.
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Meteorology 341
Homework (7) 1. Using the
following sounding records, calculate the virtual
temperature (Tv) and height correspond to each
pressure level. The surface pressure, temperature
and mixing ratio are 1008mb, 21.9 oC, and 9.6
gkg-1 , respectively. P (mb) T (oC) q
(gkg-1) Tv (K) z (m) 1008 21.9
9.6 0 989
20.9 8.4 955 19.5
6.8 898 16.2 6.2
2. On a certain day, the atmosphere has a
temperature T0 of 20oC and a pressure p0 of 1000
hPa at the surface (z00). The lapse rate is ?06
K/km from the surface to 3 km altitude ?13
K/km from 3 km to 6 km altitude. Find the
pressure p at an altitude of 5 km. 3. A moist
air parcel initially is at 500 m. Due to the
advection, the pressure of this air parcel
decreases 20 mb. Find if there is cloud forming
during this process. Assuming the process is
adiabatic the vapor pressure of the air parcel
is 8 mb at 500m and remains constant. The
vertical distribution of atmospheric pressure and
temperature are
respectively. 4.
Problem 7 on page 169