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* Reading Assignments:. All sections. 7. Hydrostatic Equilibrium. 7.1 Effective gravity. Radial gravitation by the planet’s mass Centrifugal acceleration due to rotation of the reference frame Anisotropic contributions. 7.2 Geopotential and Geopotential height.
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* Reading Assignments: All sections
7. Hydrostatic Equilibrium 7.1 Effective gravity • Radial gravitation • by the planet’s mass • Centrifugal acceleration due to • rotation of the reference frame • Anisotropic contributions
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.
7.4 Stratification of environment The environmental lapse rate: * Layer of constant lapse rate
* Isothermal Layer * Layer of Homogeneous Density
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?
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 temperaturein 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.)
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.
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,
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.
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 (z0=0). The lapse rate is 0=6 K/km from the surface to 3 km altitude; 1=3 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
