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| The Doppler radar can also see wind velocity by computing the motion
of particles in the atmosphere. However the motion of the particle
can only be seen if it is moving toward or away from the radar.
This is called the radial velocity. If
the particle is moving perpendicular to the radar beam (shown
on the left side of the figure), the radar will calculate a wind
speed of zero. If the wind is moving parallel to the radar beam (shown
on
the right side of the figure), then it can compute the total wind
speed. When the wind is at an angle then the radar sees a fraction
of the wind speed depending upon the angle of the wind direction to the
radar beam.
In order to calculate the wind speed, the radar compares the distance traveled by a particle(s) in two successive pulses and then calculates the speed of the particle in order to compute the wind speed. This can be done up to 40 times for a given point. This allows the radar to determine the radial velocity from an average of several calculations. |
