I agree with Brian, but I wonder if we can't unambiguously indicate
which direction is positive. As suggested by Brian, there is confusion
specifying this since the air velocity is downward when the pressure
tendency is positive. Can anyone think of a clearer way of expressing
the sign?
Karl
Brian Eaton wrote:
> I agree with Ag. I don't think it's helpful to use symbols for physical
> quantities. We do use symbols for mathematical quantities which seems
> unavoidable. However,
> upward_air_velocity_expressed_as_tendency_of_air_pressure has a sign
> problem. "upward" means positive values are upward, but omega is negative
> for upward motion. So the name should begin with "downward" which has the
> correct sign, or "vertical" which doesn't specify the direction. I think
> my preference would be "vertical".
>
> The table also has the entry
> upward_air_velocity_expressed_as_tendency_of_sigma which has the same sign
> problem. In addition this name uses the term "sigma" which is not
> explained in the "help". It would be helpful to have a comment that says
> "sigma" refers to "atmosphere_sigma_coordinate".
>
> As an aside, the term "expressed_as" probably should be included in the
> "guidelines" doc.
>
> Brian
>
> On Thu, Nov 27, 2003 at 12:13:38PM +0000, Jonathan Gregory wrote:
>
>>Dear Ag
>>
>>
>>>omega (Pa s-1)
>>>
>>>What was the rationale behind calling it 'omega' rather than upward_velocity
>>>or upward_wind or upward_air_velocity.
>>
>>It's because this quantity is always called omega. Systematically it could
>>be named upward_air_velocity_expressed_as_tendency_of_air_pressure but omega
>>is more familiar. upward_air_velocity (in m s-1) is also in the table.
>>
>>Does anyone else have comments on this?
>>
>>Cheers
>>
>>Jonathan
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Received on Tue Dec 02 2003 - 17:13:00 GMT
