If divergence aloft > convergence at surface, will the low
will deepen or decay? If divergence aloft < convergence at
surface, will the low will deepen or decay?
Hurricane Sandy in three cosmic-ray neutron records 1000 P re s
s u re U n c o rre c te d n e u tro n s 800 980 700 960 600 P re
ssu re , m b N e u tro n co u n ts p e r h o u r C O S M O S p ro b
e , S h a le H ills , P A 900 Shale Hills Newark Beltsville 940 P
re s s u re -c o rre c te d n e u tro n s 500 24 O ct 26 O ct 28 O
ct 30 O ct 1 Nov 3 Nov 5 Nov P re s s u re 1020 U n c o rre c te d
n e u tro n s 900 1000 800 980 700 P re s s u re -c o rre c te d n
e u tro n s 600 24 O ct 26 O ct 28 O ct 30 O ct 1 Nov N e u tro n M
o n ito r, N e w a rk , D E 3 Nov 5 Nov P re s s u re , m b N e u
tro n c o u n ts p e r h o u r C O S M O S p ro b e , B e lts ville
, M D 1000 960 As the hurricane Sandy (above) passed through the
Northeastern USA, it went over three instruments that measure
cosmic-ray neutron intensity, a neutron monitor that is sensitive
to pressure, and two COSMOS probes that are sensitive to pressure
and surface moisture. The two COSMOS probes have different
responses because one, Beltsville, experienced large rainfall,
whereas the other did not. More on that on next page. COSMOS data
are available here: cosmos.hwr.arizona.edu. The COSMOS project is
funded by the Atmospheric and Geospace Sciences Division of the
National Science Foundation. The Newark neutron monitor data show a
response to pressure drop. Data and plot are courtesy of Roger Pyle
of the Bartol Research Institute, University of Delaware. Neutron
monitor data are available here: http://neutronm.bartol.udel.edu.
Marek Zreda ([email protected]) 12
Help?
Tilt
Jet streaks (maximum in jet streams) tend to found in the base
of trough Intensify convergence Intensify divergence -storm moves
northeastward, It no longer has upper-level support of diverging
air, and storm dies out
Rossby waves 4~6 waves Wavelength 4000~8000 km
Thunderstorm Distribution A climatology of the average number
of thunderstorm days in a year 10
Thunderstorm
Cumulus Mature 12 Dissipating
Fig. 11-10, p. 320
Tornado
16
Fig. 10-32, p. 288
derived from Spanish word tornada thunderstorm tornados arise
from severe thunderstorms most tornados in central US on average
about 770 tornados are reported annually occur mainly from April to
June but all year round
Fig. 11-23, p. 331
Tornados visited NYC on September 16, 2010 The National Weather
Service (NWS) said one of the tornadoes touched down near Park
Slope in Brooklyn with maximum wind speeds around 80 miles (129
kilometers) per hour. The second tornado touched down about 2.5
miles (4 kilometers) south of Flushing in Queens and lifted about
one mile (1.6 kilometer) northeast of Bayside. This tornado was
slightly stronger with maximum wind speeds of around 100 miles (161
kilometers) per hour. Tornadoes are extremely rare in New York
City, and Thursday's tornadoes were the first time one record that
a tornado caused a fatality in the city. The last time a tornado
hit New York City was in July, when a weak tornado swirled through
the Bronx. Prior to that, two tornadoes touched down in Staten
Island and Brooklyn on August 8, 2007. Other tornadoes touched down
in 2003, 1995, 1990, 1985 and 1974. No other tornadoes were
recorded since records began in 1950.
http://data.giss.nasa.gov/gistemp/graphs/
Q: If you are confronted in an open field by a large tornado
and there is no way that you could outrun it, probably the only
thing that you could do would be to run and lie down in a
depression. If given the choice, would you run toward your right or
left as the tornado approaches? Explain your reasoning. Fig. 11-23,
p. 331
Something like
produce a rotating column of air by a large wind shear at the
surface lift the rotating column of air from horizontal to vertical
by updraft Fig. 11-23, p. 331
Where is tornado birth-column? Southwesterly wind Why
overshooting? Mesocyclone a single strong rotating updraft Rear
Flank Downdraft Why no prec. In mesocyclone? Wall cloud lower than
others why?
Importance of the Rear Flank Downdraft
Wall Cloud
Tornado structure Q: in the core of a tornado, is the flow
direction upward or downward? How strong is a tornado?
