[Understanding Weather & Climate, Books a la Carte Edition (6th Edition) #ISBN-13: 978-0321773227 #ISBN-10: 0321773225 CH 5 Atmospheric Moisture]

Diabatic /Adiabatic process

Diabatic process (e.g formation of fog)
– is involving adding OR removing energy from a system.

Adiabatic process (e.g formation of clouds)
– is involving temperature changes but no heat is added or removed from a substance – i.e ∆H = 0
(REF: [ ∆H (change in heat) =  P∆V + c∆T ])

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Extension Reading:

In terms of cloud’s formation –

Expanding air cools; Compressing air warms:
– base on adiabatic process AND 1^st law of thermodynamic

Volume of gas increasing (V↑) + Internal energy decreasing (Temp↓)  ⇒ no change in heat
[formula: Positive work + (negative temperature) ⇒ ∆H = 0]

In the atmosphere, air raise, encounter lower surrounding pressure,  it expands and cools.