ILLUSTRATIONS 125 
Spring Showers 
WASHINGTON. DC 
MAY 6&7 1935 
S RAINFALL 
& ZALTITUDE 
MAY 6 
w TENPERATURE 
B PRESSURE 
° 
° 
PRESSURE 
AIR MASS AND WEATHER SEQUENCE PASSING OVER WASHINGTON, D. C., May 
6-7, 1935.—A time-line cross-section in which the earliest hour is at the right. 
This unusual diagram was made up from a study of the surface observations 
and the synoptic cross-sections at the Weather Bureau in Washington for the 
purpose of summarizing the climate of the whole month in terms of air masses 
and fronts. However, it incidentally also shows an interesting typical sequence 
in the upper air. Note the showery rain (stippled bars) from the Te being 
occluded and lifted between Np and older Np; and the location of Ts, which is 
characteristic—the rain stops abruptly when it arrives. The pressure and 
temperature traces at the ground are typical. There was a thundershower at 
the cold front. The TG sector is of course cloudy, the Ts/NP zone nearly clear. 
(From: Botts, Sept., 1937, BULL. p. 290-297.) , 
WASHINGTON, D C 
MAY I2 & 13, 1935 
SRAINFALL 
a Z ALTITUDE 
MAY t2 
o 
2 
2 
& 
= 
= 
e 
°F 
= PRESSURE 
Another of Bott’s sections, showing pronounced eold-front rain from a 
cold-front-type occlusion. 
