Difference between LHF and evaporation rate?

[vishal]

I have a doubt. What is the difference between the latent heat flux (LHF) and evaporation rate? If both are same than my concept is ok. If it is different than what are the basic equations to compute these two parameters? Kindly write down few sentence regarding the same instead of sending more links.
Regards
Vishal

[vinu]

Hi Vishal,

my view.

From the wording itself, you could infer, 'Latent Heat Flux' is something
related with 'Heat' and 'Evaporation rate', is
something related with 'a quanity of matter per unit time'.

Latent Heat flux:- By definition, it is the amount of heat released when
matter is converted from one state to another. For example, when water
converts to vapor, it is Latent heat of evaporation (still it is the amount
of Heat).

Evaporation rate:- By definition, it is the amount or quantity of matter
that is evaporated in unit time.

Relate these two:- If you examine the Units of LHF, it is W/m2 and
Evaporation rate, E is Kg/s. If E is represented in flux form, it is
Kg/m2/s, i.e. amount of water evaporated per unit area in unit time.
Now, suppose, L.H.F = Rho . Lv . Cd . U . (Qs - Qa), where Lv is the Latent
heat of vaporization (unit Joul/Kg)., Rho=density, U=wind, Qs,Qa = specific
humidity (saturated and air, respectively) and Cd = drag coeff.
If you put Lv to the left hand side of this equation,
then L.H.F/Lv = Rho. U. (Qs-Qa), whose unit is Kg/m2/s, and it is
equivalent to 'Evaporation rate (in flux form)'.

Simply, Evaporation rate is equal to the Latent Heat Flux, 'but scaled
by a factor 'Lv'. Here, Lv take cares to convert Heat into equivalent
amount of matter, from where, that much of heat is being derived during
a convertion of matter from on state to another.
Lv:- It is the amount of heat released when unit mass of matter convert
from one state to another, (am i miss leading?).


Please waite. It will be useful refering this
book, (if available),
Thermodynamics of Atmosphere and Ocean by
Curry and Webster, International Geophysical Series, Volume 65.


PS:
Also, Please be patient to visit the links that members suggesting.
It may be directing you to more authentic writting (book/e-notes
or papers).

-Thanks
-

[vishal]

Vinu,
Thank you very much to improve my understanding. Since long I had been confused when I read about these two parameters simultaeously. Your explanation really helped me a lot. If it is possible, please explain me a bit more if you have more idea regarding this topic. This kind of explanation is quite useful instead of going through a huge binding book.

With regards
Vishal