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301 
APPENDIX 
Data describing the first raindrops collected on 
August 16, 1957 between 11 h 20 m and 
11 h 22 m MST 
Collection surface: Whatman *1 filter paper 
(31 em dia) treated with methylene blue dye 
(see Fig. 7). 
(a) Drop data: 30 drops collected in 120 see 
(b) Distribution of drop sizes: 
2 drops 3.8 mm diameter 
Piet 3.6 to 3.7 mm diameter 
6 3.4 to 3.5 
iG 3.2 to 3.3 ie 
4 3.0 to 3.1 
3) 2.8 to 2.9 
1 2:6: to 2.7 
4 2.4 to 2.5 
1 2.2 mm diameter 
(c) Drop concentration: The rain collection 
area was 760 em* and the approximate distance 
fallen in two minutes was about 1.2 km, so that 
the 30 drops came from an air volume of about 
90 m*. The mean drop concentration was 0.3 
drop m™*. 
(d) Rainfall rate: The water contained in the 
30 drops amounted to 0.5 em* over a 760 em? 
area. This is a rainfall rate of 0.2 mm hr™. 
(e) Liquid water concentration in the first 
rain: 5 X 10° gm m™® (ie. the mean liquid 
water content in the lower portion of the cloud 
is enriched by 1 part in 200 by this first rain). 
Via. 
7—Photograph of filter paper stained by first raindrops, August 16, 1959 
