Post on 16-Feb-2021
4.7. The 2nd law of thermodynamics and Clausius-‐Clapeyron equa
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qs ≈0.622es
p
es = eo ⋅ expLRv⋅
1To−
1T
%
& '
(
) *
%
& '
(
) *
where qs : saturation mixing ratio; p : air pressurees : saturation vapor pressureeo : saturation vapor pressure at a reference temperature, To,often To = 273.15K = 0
oCL : 2.5 ×106 J deg-1, latent heat of vaporation, Rv = 461 Jdeg
−1 kg−1 : gas constant for water vaporT : temperature;
What control atmospheric water vapor: • The satura
Discussion:
• Why do storm intensity and extreme rainfall tend to increase, esp. in tropics, under a warmer climate?
Summary: • Most of
Exercises-‐Moist thermodynamics
• We oOen experience a cool downdraO air during a summer thunderstorm. – What causes a cool downdraO in the thunderstorm? – Compare air temperatures at 1000 hPa for these two cases. In both cases, air
temperature was 0C at 700 hPa. In the first case, a dry air subsides to 1000 hPa. In the second case: 5 g/kg liquid water evaporated in the air as it subsides to 1000 hPa.
2. Air at 1000 hPa and 25C has a wet bulb temperature at 20C. Using the in
SkewT-‐lnp chart: – Find the dew-‐point, Td, – If this air were expanded un
3. Water vapor feedback is the strongest atmospheric feedback to climate change. • Assuming that the rela
4. Plot the temperature profile and use the Te (ambient temperature) and Td (dew point) at the surface to determine the pressure level of free convec
Te values are measured at various pressure levels. We need to compute Tc for convec
Solu%on for 4b: To compute CAPE, we use Te and Tc values in each atmospheric layer between
the LFC and LOC given in the above discussed tables and the formula
• Calculate CAPE uses formulas (2) for Td=20C and 15C, respec
Materials covered by Quiz-‐2 (April 7th):
• All materials in the thermodynamics of dry and moist air