Agent Smith wrote:
Harold Brooks wrote in
T:

In article 02,
agent- says...
Harold Brooks wrote in
T:

In article 02,
agent- says...
Can anybody recommend a good website with a video of the radar of
the tornadoes as they crossed Tenessee, two days ago? No live
action footage, please, just radar data. TIA
http://www.srh.noaa.gov/bna/surveys/...508/RadarLoop_
020508.g
if
Is there any way to zoom in and pan around, to see the individual
tornadoes?
WYSIWYG, although you would very rarely see the individual tornadoes
in any event from the radar.

Shouldn't that depend on what the radar display is calibrated to
reveal?
Base Radial Velocity

This is the velocity of the precipitation either toward or away from the
radar (in a radial direction). No information about the strength of the
precipitation is given. This product is available for just two radar
"tilt" angles, 0.5? and 1.45?. Precipitation moving toward the radar has
negative velocity (blues and greens). Precipitation moving away from the
radar has positive velocity (yellows and oranges). Precipitation moving
perpendicular to the radar beam (in a circle around the radar) will have
a radial velocity of zero, and will be colored grey. The velocity is
given in knots (10 knots = 11.5 mph).

Where the display is colored pink (coded as "RF" on the color legend on
the left side), the radar detected an echo but was unable to determine
the wind velocity, due to inherent limitations in the Doppler radar
technology. RF stands for "Range Folding".

Determining True Wind Direction

The true wind direction can be determined on a radial velocity plot only
where the radial velocity is zero (grey colors). Where you see a grey
area, draw an arrow from negative velocities (greens and blues) to
positive velocities (yellows and oranges) so that the arrow is
perpendicular to the radar beam. The radar beam can be envisioned as a
line connecting the grey point with the center of the radar. To think of
it another way, draw the wind direction line so that the wind will be
blowing in a circle around the radar (no radial velocity, only
tangential velocity).

In order to determine the wind direction everywhere on the plot, a
second Doppler radar positioned in a different location would be
required. Research programs frequently use such "dual Doppler"
techniques to generate a full 3-D picture of the winds over a large area.

Finding Tornadoes

If you see a small area of strong positive velocities (yellows and
oranges) right next to a small area of strong negative velocities
(greens and blues), this may be the signature of a mesocyclone--a
rotating thunderstorm. Approximately 40% of all mesocyclones produce
tornadoes. 90% of the time, the mesocyclone (and tornado) will be
spinning counter-clockwise.

If the thunderstorm is moving rapidly toward or away from you, the
mesocyclone may be harder to detect. In these cases, it is better to
subtract off the mean velocity of the storm center, and look at the
Storm Relative Mean Radial Velocity.

-wunderground