neufer wrote:"Similar" low temperatures at an altitude of 2800 m would be more like -40ºC ... is that what you mean?
No, what I meant is that I've looked at sky temperatures when the surface temperature is -25°C and not seen evidence of an inversion layer... that is, I've seen what appears to be a monotonic decrease in temperature from -25°C at the ground to -40° or less at 10 km.
A -40ºC temperature at night with no wind and would virtually guarantee that there is a strong inversion.
This is the point I don't understand. Is it because of the radiative temperature drop of the surface? I certainly see
that effect strongly on calm evenings, but it only seems to produce cold air up to a few tens of meters most of the time.
Have you compared your 8-14um map of the sky analysis with actual temperature soundings; surely you must underestimate what the warmest layer actually is.
I use a technique developed for converting allsky temperature measurements to a vertical profile. It depends on the fact that when you look at different zenith angles you are looking through different depths of atmosphere. Many observatories use this method, and it has been tested against actual sounding data, but I haven't made any such test myself at my location.
[quote="neufer"]"[b]Similar[/b]" low temperatures at an altitude of 2800 m would be more like -40ºC ... is that what you mean?[/quote]
No, what I meant is that I've looked at sky temperatures when the surface temperature is -25°C and not seen evidence of an inversion layer... that is, I've seen what appears to be a monotonic decrease in temperature from -25°C at the ground to -40° or less at 10 km.
[quote]A -40ºC temperature at night with no wind and would virtually guarantee that there is a strong inversion.[/quote]
This is the point I don't understand. Is it because of the radiative temperature drop of the surface? I certainly see [i]that[/i] effect strongly on calm evenings, but it only seems to produce cold air up to a few tens of meters most of the time.
[quote]Have you compared your 8-14um map of the sky analysis with actual temperature soundings; surely you must underestimate what the warmest layer actually is.[/quote]
I use a technique developed for converting allsky temperature measurements to a vertical profile. It depends on the fact that when you look at different zenith angles you are looking through different depths of atmosphere. Many observatories use this method, and it has been tested against actual sounding data, but I haven't made any such test myself at my location.