some of these errors by a subjective interpretation of the
Rawinsonde Observations (RAOBs), as discussed in the
following sections.
INTERPRETATION OF RAOB LAYERS
WITH RESPECT TO CLOUD LAYERS
The following diagrams (figs, 4-16, 4-17, and 4-18)
illustrate the behavior of a rawinsonde during cloud
penetration. These diagrams are correlated with aircraft
observations or the heights of cloud bases and tops from
aircraft flying in the vicinity of an ascending rawinsonde.
The difference in time and distance between the aircraft
and sounding observations was usually less than 2 hours
and 30 miles, respectively. Some of the aircraft reported
only the cloud observed above 15,000
Figure 4-16.-Example of inferring clouds from a
RAOB with an active warm front approaching from
the south.
feet; others reported all clouds. In figure 4-16 through 4-
18, the aircraft cloud observations are entered in the
lower left corner of each diagram under the heading
cloud; the surface weather report is entered under the
aircraft cloud report. Where the low cloud was not
reported by the aircraft, the height of the cloud base may
be obtained from the surface reports, Aircraft height
reports are expressed in thousands of feet, pressure-
altitude. The temperature, frost point, and dewpoint
curves are indicated by T, Tf, and TD respectively.
In figure 4-16, a marked warm front is approaching
from the south. Moderate continuous rain fell 2 hours
later. At 1830 UTC, an aircraft reported solid clouds from
1,000 to 44,000 feet (tropopause). The 1500 UTC
sounding shows an increasing dewpoint depression with
height and no discontinuity at the reported cloud top of
15,000 feet. A definite dry layer is indicated between
Figure 4-17.-Example of inferring clouds from a
RAOB with a middle layer and no precipitation
reaching the surface
4-15
