Meteorology 302.01, Spring 2004
Class Notes for April 28, 2004
Kenny Kapoor
Rodrigo Marquez
Assignments
Vasquez: Chapter 3, pp. 50-51, 54-56,58-61 67-77;
Chapter 4, 78-86, 91-95; Chapter 5, 118-124; 170-172, 184-186; Appendices,
browse, 271-274
Housekeeping
Midterm #2: (Bring Scantron Form 882 and Number 2
Pencil)
Section 1 (Only) Moved To Friday 30 April
Dynamic Lows & CAPE Review
Dynamic Lows- have trough on left and ridge on right
If there is any CAPE from 0 to 500mb, CIN will also
be plotted
CIN = inhibition for storms, prevents thunderstorms
from developing
Partially unstable air is needed for thunderstorms
to develop
Systems move with a forward speed of 50mph
Common Thunderstorm
Most thunderstorms are not severe unless they
develop in areas of high CAPE
In thunderstorms water droplets get taken above the
freezing level and turn into hail
If they get caught in another updraft they gain
another layer of ice
The stronger the updraft, the stronger the hailstone
can become
Sometimes hailstones get so large, updrafts can no
longer suspend them so they fall to the surface
With 100mph updrafts you can get hailstones the size
of softballs (they reach the ground as ¾ inch or greater
Downdraft can make temperature decrease by 20
degrees
Wind sheer, Downbursts, and Lightning
Horizontal wind sheer- 40mph updrafts and downdrafts
(the stronger the greater the danger)
In general updrafts are between 20-40mph
Vertical wind sheer- strong when jet stream is
present
If wind speed exceeds 57mph it is called a downburst
(at this point it is a severe thunderstorm)
Cloud to ground lightning- most dangerous because of
risk of being struck
Hypothesis on why lightning occurs: The ice that
forms at top of the thunderstorm called hailstones collide with each other
knocking electrons off. Once there is enough energy the cloud discharges the
electricity