L3 comminications Stormscope II Series Pilot's Manual page 18

Anatomy of a Thunderstorm
b.The friction between the opposing air currents causes
c. Electrical discharges occur as the accumulated masses
d.All electrical discharges radiate electromagnetic signals
Figure
tected in an area is directly related to the amount of convec-
Figure 2-2. Discharge Rate a Function of Wind Shear
2-2
electrical charges in the area to separate. As positive (+)
and negative (–) electrical charges are separated, they
accumulate in masses of similar charges (positive
charges near the top of the cloud and negative charges
near the bottom).
of separated positive and negative charges attempt to
rejoin. These discharges continue to occur repetitively
as long as the convective wind shear persists. A few of
the discharges are visible as lightning, but most electri-
cal discharges occur within a cloud or between clouds
and are hidden by those clouds. Only a small percent-
age of discharges occurs between the clouds and the
ground. Cloud to ground lightning occurs when the
negatively charged lower part of a cloud induces a
positive charge on an object on the ground. The
immense charge separation finally breaks down the
insulating air and a discharge occurs dumping negative
charge from the cloud onto the object and the sur-
rounding ground.
in all directions close to the speed of light. The electro-
magnetic signals have unique characteristics and
varying rates of recurrence and signal strength.
shows that the rate of electrical discharges de-
2-2
Light
Increasing Turbulence Due to Convective Wind Shear
Chapter 2 – Storm Mapping Principles
Moderate
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Stormscope
WX-950 Pilot's Guide
Severe