.
.
'
-
:
.
ee eel Pane ed em atid ae ttnde BE el toe
141
1600
1
-”
1400 -—-
ws 24 APRI969 1630
e
eae APR 1969 2100
PRESSURE HEIGHT,
meters
1200 F—
1Q00 F—
800 [—
600 >—
\
25 APR
\N"
24 APR 1966 1220
!969
400 F—
200 t—
TEMPERATURE, °C
Fig. 103.—Vertical temperature profiles, Midway Airport, April 24-25, 1969
CST at Argonne. The winds were southwest at 8 to 10
mph. Clouds were broken at 10,000 feet with a 0.9
cloud cover at Midway.
The Cineinnati thermistor system was flown on
January 14, 1969 by Argonne personnel in a rented
light plane (Cherokee 140). An adiabatic lapse rate
was observed up to the solid cloud layer at 1400 feet
over the Lewis Lockport Airport.
(a lakefront site). A few soundings were made at. other
locations.
A large, strong, high pressure area was moving from
NWto SE across Chicago during the flight program.
As the center of the high pressure passed, the winds
veered from north at 8 mph at the start of the pro-
gram through ESE at 5 mph at 2100 CST on the 24th,
through S at 4 mph at midnight to SE at 4 mph by
the end of the period. The sky remainedclear.
The airplane flights conducted between 1200 CST
on April 24th and 0600 CST on April 25th are illustrative of how an aircraft can be used to measure both
The time variability of lapse rate at Midway is
shown in Figure 103. Considerable warm advection oc-
Midway Airport (a city location} and Meigs Airport
turnal inversion extended to 980 ft by 2100 CST; the
intensity but not the depth of the inversion increased
the space and time variability of lapse rate in the
area. The thermistor-bridge system was used every
four to five hours to make profile measurements at
Lewis Airport in Lockport, Illinois (a rural area),
curred above 1300 ft between 1220 and 2100 CST.
The mixing depth decreased from 2900 ft to 1640 ft
between 1220 and 1630 on the 24th. The surface noc-