# Wind Measurement

The meridional velocity is the distance, *r* · , divided by the time difference, *t*. Since the radius
is given in Km's and the time is given in hours we need factors of
1000 and 3600, respectively, to convert to meters per second. If
is given in degrees then:

*V* = 1000 *R*() ·
(/180)(_{1} - _{0})/(3600 *t*)

To calculate the zonal velocity we need to calculate the
displacement along a latitude circle, (*i.e.*, /
360), during the time interval *t*.

= (*t _{1}*) - (

*t*)

_{0}*U* = 2 *R*(<>)
cos(<>) · (1000/3600) ·
/(360 *t*)

Alternatively, we can calculate the period of rotation of
the measured feature, *P*, and define the wind relative to the system
of measure, *P _{ref}* as follows:

*P* = 360 *t*/[ + (360
*t*/*P _{ref}*) ]

so that,

*U* = 2 *R*(<>)
cos(<>) · (1000/3600) ·
( 1/*P* - 1/*P _{ref}* )