PPRuNe Forums - View Single Post - Saturation
Thread: Saturation
View Single Post
Old 25th May 2005 | 14:37
  #6 (permalink)  
Send Clowns

Jet Blast Rat
 
Joined: Jan 2001
Posts: 2,081
Likes: 0
From: Sarfend-on-Sea
Not bad, HWD

Lifting a parcel of air without exchanging energy with the environment (that is the meaning of "adiabatic") will always cause significant drop in temperature due to significant drop in pressure. This will eventually lead to condensation except for the driest air.

A drop in pressure without commensurate change in temperature (option C, while ambiguous, appears to mean this) will not cause condensation. Any effect of pressure alone on the capacity for air to hold water is negligible and not within the syllabus, as far as I am aware. Our met instructor is on leave so I cannot check, but I certainly never learnt anything about that when I sat the course (and I got 96%, so it is clearly not essential knowledge!). I suspect there is some effect, but not enough to worry a poor pilot!

Twotter

IBLB is actually correct, if a little over technical for most ATPL groundschool students, more like a physics lesson. The energy taken from the thermal energy goes into the work done in expansion. Imagine the air surrounded by a balloon - it would expand, needing energy.
Send Clowns is offline