6. Oblateness versus Diameter (Full Screen)
The full screen
representation of the diagram "Oblateness versus Diameter" can be
selected from the Main Screen by moving the mouse cursor on top of the
according diagram icon and doubleclick with the left mouse button. The results
presented in this diagram are the geometrical mean of the ratios heigth / width
of a raindrop's front and side view. Strictly speaking these results are not
really the raindrop's oblateness, but only an approximation.
6.1
Menu Buttons
button: RUN
Pushing this
button draws the diagram for the given filter settings. A dot is set for each
drop at the corresponding (equivolumetric sphere diameter, oblateness)
position. The mouse cursor changes its appearance to an hourglass cursor in Run-mode,
and the RUN button toggles to be the STOP button. Drawing can be terminated by
pressing the STOP button.
button: MAIN
Pushing this
button returns control to the Main Screen.
button: HELP
Pushing this
button displays a help window.
button: COMP
If this button is
pushed, graphs taken from the literature and showing relations between
equivolumetric sphere diameter and drop oblateness will be drawn.
button: GRID
Pushing this
button draws ten yellow crosses into the Oblateness versus Diameter diagram,
indicating the nominals of the calibration sphere values. The ten crosses
correspond to the following diameters: 0.5, 1, 2, 3, 4, 5, 6, 7, 8 and 10 mm.
This menu option allows a quick and easy check of the calibration status of the
instrument.
button: N(H/W)
Pushing this
button invokes the Oblateness Distribution analysis.
button: Calibrate
Pushing this
button allows the user to make a software adjustment to the measurement result.
Previously selected output_data will be processed and written to 2 files named corr_in.dat
and corrfact.dat.
6.2
Diagram Header
The diagram header
contains information on filter settings and also includes the following fields:
6.3
Comparison with Literature Models
The graphs taken
from the literature for oblateness versus equivolumetric sphere diameter are:
6.3.1 Drop
Oblateness after Pruppacher and Beard (1970)
For big D H/W(D)
is given as:
where D is the
equivolumetric sphere diameter in mm. For small D here the graph is drawn as
H/W(D)=1.
6.3.2 Drop
Oblateness after Poiares Baptista (1992):
For big D H/W(D)
is given as:
where D is the
equivolumetric sphere diameter in mm. For small D here the graph is drawn as
H/W(D)=1.