CFIRCULAR N0. 19
KILLIN G FROST `AND LENGTH OF GROWING I
SEASON IN VARIOUS SECTIONS OF
. KENTUCKY? ‘
BY F. . WALZ, { _
Professor of Meteorology, U. S. Weather Bureau.  
Infarming operations the farmer, every season, is con-  i_ ·;
fronted with certain climatic and weather risks, Therefore,   }
to be successful, he should study the climatic conditions of his t   
section and, in some degree, know the risks that come to him   _
from climatic causes, in the raising of any crop. Favorable and I l A
unfavorable weather conditions are of the greatest importance e i
to him at all times. I I o _‘
Among the risks that he faces each season is that of dam-   V j
age by late frosts in spring and earl): frosts in autumn. Frost 1 A *
is the moisture of the air condensed at freezing temperature »   »
on plants and other objects near the surface of thc earth. The Q I  
temperature, therefore. of the surface one which frost appears t T
must necessarily he as low as 32‘ F. This paper presents a `  Q. .  
summary of the results of a study of the dates of the last kill—   I  
ing frost in spring and the first. killing frost in autumn, taken —   ‘  
— from the records of the various eo-operative and other \Veather   .  
p A Bureau stations that have been maintained in Kentucky, _ U;  
especially those having a record of 20 grears or more.      
These records have heen studied and analyzed. etnpllogvingt 4 , ij  
mathematical methods used in the investigation of statisties  
and prohahilities. The average dates of last hillliny; frost in  
spring and first killing frost in fall, at each station, were ·care·  
fullly computed. These average dates. it roost he ttntlerstood.   .l"-  
however, do not inean that they are the trétiall or »%t'~tr¤t Th"'  
expected dates of last and first kilhrig frost. 'lfhegr are ontlgr  
7 ‘@etettl rtrorn an :t,»~ap·¤·r read tn=··¤'~~¤·r·e th¤·~ l»d rn tt.¤·¤~ !tllo~rnt1*.¤D;-‘ Kh'»¤··att1t,»&: Et§~¤;— 4·    
‘.U»~-W .llt1.D}‘,, INET. , yfiy-f*_‘”
_ tr lflt It ,   
1 >  
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I s t ix., l
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