[NARCCAP-discuss] definition of specific humidity

[Seth McGinnis]

Hi Ethan,

In the atmospheric sciences, specific humidity means definition #2, mass of
water / total (moist) air mass.   Definition #1, mass of water / dry air mass,
is referred to as the mixing ratio.  Note that, in general, they'll differ by
less than 2%.

Cheers,

--Seth

----
Seth McGinnis
NARCCAP Data Manager
Associate Scientist
IMAGe - NCAR
-----


On Tue, 22 Jan 2013 21:09:05 -0500
 Ethan Bodnaruk <ebodnaruk at gmail.com> wrote:
>Dear NARCCAP staff/users,
>
>I am trying to figure out how to calculate the dewpoint from surface
>specific humidity and other data (temp, pressure) but I see two conflicting
>definitions of specific humidity:
>
>1)  mass of water in air / dry mass of air
>
>2)  mass of water in air / total mass of air
>
>Which of these two definitions accurately describes the huss (surface
>specific humidity) variable?
>
>Thanks so much for your clarification!
>
>Best,
>Ethan
>
>-- 
>Ethan Bodnaruk
>M.S. Nuclear Engineering
>Ph.D. Student, Ecological Engineering
>SUNY Environmental Science and Forestry
>1 Forestry Drive
>Syracuse, NY 13210
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