LS 
[ADAMS] CLIMATIC FACTORS IN RELATION TO PLANT LIFE 121 
In measuring evaporation the total amount for the summer 
period should be determined as well as its relation to rainfall through- 
out the season. This relation may be fairly gauged by reckoning up 
the number of five-day periods with evaporation in excess of rainfall. 
When several successive five-day periods are characterized by an 
evaporation exceeding the rainfall a drought may result. Such a 
drought, if prolonged, may seriously affect the growth of plants; 
accordingly the duration of the longest drought during the summer 
season is of importance. This is taken to mean the greatest number 
of successive five-day periods with evaporation in excess of rainfall. 
As very few figures relating to evaporation in Canada are available 
the following are some observations made by myself at Ottawa 
during the summer of 1915. They are grouped for the most part 
but not entirely according to the five-day period. (Table XII). 
TABLE XII. 
EVAPORATION AND RAINFALL AT OTTAWA, 1915. 





Evaporation Rainfall 
(Inches). (Inches). 
civil ORR Nh dys ou re | ? -50 
i CORRE Le se ee ea | +45 -75 
Et de na re | 60 30 
“ NG 2 OR SE SE SRE De +30 -40 
1 1 IO et Oh aiid ee a | -45 -20 
CBee OnSite nl RES ae ner 1-00 -15 
ONE SE CREER E | -90 -00 
TO RL cu x | 1-00 -10 
oils SO ee Oe à +75 2255 
GAO): Leet et pe -80 -55 
ee PAIS mers de il: à | -75 -15 
TO SUR Re LS D cu | -85 -00 
Aad ee SE ONCE ARE cia, -70 -45 
s CUT) SAR TE eee -65 -15 
A TR A eee | -00 -00 
SO ON nier Au. 50 95 
Be PDA AOR A eee aig te a -85 30 
sD fe St ee ka a Le -40 00 
TROT ES ER Eo | -75 1-05 
‘ (C= NN es AE eee ae -45 1-75 
I ISAC TES NS -70 90 
elt LEA Ta a ge EE RE EEE AR -55 15 
3) I ES TRE UE -50 2-55 
DELO lines AE A ed Ps Le i, -15 85 
