Hello All,

I'm confused over what Theta E is measuring.

Does it measure the temperature of an airmass, or the temperature of a
parcel of air that is rising?

Joe
Wolverhampton
175m asl

"Joe Egginton" wrote in message
...
Hello All,

I'm confused over what Theta E is measuring.

Does it measure the temperature of an airmass, or the temperature of a
parcel of air that is rising?

Joe
Wolverhampton
175m asl

T_e is the equivalent temperature. Effectively this the temperature that a
parcel of moist air would achieve if it were lifted cooling at the saturated
adiabatic lapse rate (SALR) until it is so cold that the vapour pressure is
effectively zero and all water vapour is precipitated and then brought back
down to the same level warming at the dry adiabatic lapse rate (DALR).

For theta_e is potential equivalent temperature at a standard pressure
level, usually 1000hPa, so assuming you began at a higher level than
1000hPa, you simply continue to warm the parcel at the DALR until you reach
1000hPa.

The lapse rate of theta_e will tell you something about the stability of the
atmosphere. Slightly simplistically, a decrease with height implies an
unstable layer, an increase with height, a stable layer. Theta_e should be
pretty much constant with height within a convective cloud.

Steve wrote:
"Joe Egginton" wrote in message
...

Hello All,

I'm confused over what Theta E is measuring.

Does it measure the temperature of an airmass, or the temperature of a
parcel of air that is rising?

Joe
Wolverhampton
175m asl


T_e is the equivalent temperature. Effectively this the temperature that a
parcel of moist air would achieve if it were lifted cooling at the saturated
adiabatic lapse rate (SALR) until it is so cold that the vapour pressure is
effectively zero and all water vapour is precipitated and then brought back
down to the same level warming at the dry adiabatic lapse rate (DALR).

For theta_e is potential equivalent temperature at a standard pressure
level, usually 1000hPa, so assuming you began at a higher level than
1000hPa, you simply continue to warm the parcel at the DALR until you reach
1000hPa.

The lapse rate of theta_e will tell you something about the stability of the
atmosphere. Slightly simplistically, a decrease with height implies an
unstable layer, an increase with height, a stable layer. Theta_e should be
pretty much constant with height within a convective cloud.




Thanks Steve, I've noticed in my studies that in an unstable atmosphere
the Theta E temp decreases with height, while vica versa with a stable
atmosphere.

Though so far my artificial neural network hasn't learned the above, on
the other hand, my Knowledge Based System works a treat with the rules of:


ThetaE x mb ThetaE y mb = unstability
ThetaE x mb ThetaE y mb = stability

Joe
Wolverhampton
175m asl