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<br />iIJ""'''''''''' .-
<br />
<br />."'"_.w_. _ <_'"'~_
<br />
<br />.,'. ~.'=, ,'j'. ~_'.W ,,",'iT;,." c,;..,.",. .:;..,C,..."""-.,~.."",,.;-...- . ;;.,,;;.:. .. -.. .,. . ......:.. ._'-:""'"
<br />
<br />.~, ...._..:...'.-'.~-"
<br />
<br />5.2
<br />
<br />Satellite Summary
<br />
<br />It
<br />
<br />Satellite imagery for each of the six
<br />days was examined for approximately 2300 GMT, The
<br />grid field used in calculating the vertical vel-
<br />ocity was placed over the imagery and the cloud
<br />systems in each element were classified according
<br />to cloud class, meso-structure and synoptic type.
<br />
<br />Some 104 grid elements were compared
<br />for cloud class and the estimated vertical velo-
<br />city. The cloud classes were divided into two
<br />groups: (1) clear and small cumulus, and (2)
<br />cumulus-congestus and cumulonimbus (Fig. 10). A
<br />t-test was performed upon the estimated vertical
<br />velocities of the two groups. It was found that
<br />the null hypotheses was rejected at the .034 level.
<br />
<br /> ,
<br /> . , , ,
<br />. , . ~ p ,. , ..
<br />'16 ~ .k .
<br /> '0
<br />
<br />!'
<br />,.
<br />n
<br />H.
<br />if ·
<br />" .
<br />~.
<br />, . .
<br />. . .
<br />, . .
<br />, ,.' ....,
<br />,.,.".......
<br />. . . F . , . ,.. . .. .
<br />{
<br />8
<br />
<br />i
<br />
<br />-;
<br />
<br />. , r
<br />-io
<br />
<br />CU" AND C8
<br />
<br />;
<br />
<br />elF!. AND CU
<br />
<br />.
<br />
<br />.
<br />. . . .
<br />
<br />J
<br />. . , .
<br />
<br />.
<br />. .,
<br />. . . .
<br />.......
<br />
<br />. .
<br />."0
<br />
<br />".i
<br />
<br />:u
<br />
<br />';0
<br />
<br />.:0
<br />
<br />'0 s 0 '5
<br />VlIlllCAl ViLJClTY C<M/liEe)
<br />~
<br />
<br />-
<br />
<br />Figure 10. Frequency distribution of
<br />n~ber of grid elerrer.ts versus computed vertical
<br />velocity for (1) clear and cumulus cases and
<br />(2) cumulus-congestus and cumulonimbus cases. The
<br />letter F represents those grid elements along the
<br />front range or in eastern Colorado.
<br />
<br />5.3
<br />
<br />Model
<br />
<br />e
<br />
<br />The model diagnosed a full range of
<br />convective development from no clouds in the no-
<br />lifting experiments on July 2, 1977 and August 24,
<br />1977, to deep convection with n~Terous thunder-
<br />storms in the case with 20 em s lifting on
<br />August 24, 1977. On August 24, 1977, an intense
<br />line of deep convection developed in the region
<br />of preferred isentropic vertical lifting over
<br />northwest Colorado (Fig, 7&8), The model simula-
<br />tion of convective development in this case pro-
<br />vides a good example of model response to meso-
<br />scale lifting. The thermodynamic response to
<br />lifting is shown in Figure 11. Here on a SKEW-T
<br />log P diagram, we see the sequential change of
<br />temperature and dew point for each hour as the
<br />model simulates cloud-environment interactions
<br />and lifting. The arrows indicate the direction
<br />of change as the simulation proceeds, Note the
<br />surface warming, and low level increase in dew
<br />point temperature: however, again the dew point
<br />increases due to the upward advection of moisture.
<br />The relatively stable layer from 50 to 17 kPa is
<br />adiabatically cooled and moistened by lifting.
<br />In the cloud top region from 17 to 12 kPa, cloud
<br />top evaporation results in a saturated super
<br />adiabatic layer. The model diagnosed cloud top
<br />height. visual (condensation level) cloud base
<br />
<br />height, and dry thermal base height arro shown in
<br />l~igure 12. The simulated convectivE' development
<br />with top heights of 14 km agreed ,~cll with ob-
<br />served radar tops.
<br />
<br />rlNAL SOUNDING AT IS HR 0 ~IN
<br />
<br />
<br />10
<br />
<br />.70
<br />
<br />"0
<br />
<br /> LEGEND
<br /> . . CASE I
<br /> .. CASE 2
<br /> . , CASE 3
<br /> .. CASE ~
<br /> 20 . . CASE .S
<br />if 30 Ii
<br />~
<br />u
<br />; ~O
<br />u
<br />'"
<br />..
<br /> 50
<br /> 60
<br /> 70 .Q
<br /> ag
<br />
<br />1110
<br />
<br />
<br />-il
<br />
<br />TEMPERATURE I C I
<br />.at 2.1 "..a.,.. .....to. I'V1.JUt.1CIl.XII. 1l'l.... ,_ II l'!t ~ .~..... tL JX\Sl11.
<br />
<br />Figure 11. .SKEWT-T, log p diagram showing
<br />the thermodynamic response to lifting fOlr August
<br />2.', 1977.
<br />
<br />CLOUD BASE AND TOP VERSUS TIME
<br />
<br /> If.a
<br /> It.D
<br /> U.O
<br /> 10.0
<br />~[
<br />.' ...
<br />li
<br />~1
<br /> ...
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<br /> 2..
<br /> o.~ "
<br />
<br />..- - - -.... - - -~. -......
<br />
<br />/
<br />/
<br />/
<br />/
<br />/
<br />/
<br />/
<br />/
<br />/
<br />/
<br />
<br />o
<br />
<br />
<br />o
<br />
<br />o
<br />
<br />Ii
<br />
<br />Ii
<br />T1r'C ILSTI
<br />
<br />-r--
<br />..
<br />
<br />"
<br />
<br />1'(;50 2.1 rrJ..2'5I.2f1. .......10. JVT-roo.1lXl.2OQ. OT..{,Q. ..... II IS ~.2S AIQIO- a. 11081118
<br />
<br />I"igure Ii. ':.'i: ..,-::"i:.ht plot of diagnosed
<br />cloud top height : 6: .::).~'~,.:.:i. cloud base height
<br />(0) and dry thermc::'. :.:,~c :,.z:ight : 0) .
<br />
<br />184
<br />
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