氣壓低(山頂)溫度低, 點解會氣壓低溫度高? (求物理解)

1. I think it is the reverse. High temperature leads to low pressure, and low temperature leads to high pressure.
Density of air over high temperature region is less dense, it tends to rise. As a result, the pressure over that region decrease.
Likewise, density of air over low temperature region is denser, it tends to sink. Thus causing a high pressure. The decrease of pressure in this case is due to less air above.

The above explanation is applicabe at sea levels. Temperature and pressure decrease over altitude is a different phenomenon.

2. Your question s not clear...what do you mean by "下沉區比上層壓", please clarify!

3. Water vapour does have specific heat capacity. A lowering of temperature needs to cool down the water vapour. For a satuated air, when the water vapour condenses because of cooling the air, latent heat is released, which would in turn heat up the air.