PAPERS BY MEMBERS 1 1 7 



southern sky, the chance of rain at your locality is less, as the 

 storm may pass to south of you. 



Cirrus in the lower half of the northern sky, having the 

 form that seems to spread outward from the northwest, but 

 at the same time moving from due west, indicate rain to 

 north and northeast of your locality within probably 12 

 hours. A similar appearance in the north wnth the cirrus 

 covering the northwest sky and moving rapidly out irc-m the 

 northwest toward the zenith, indicates rain at your locality 

 usually within 12 hours. 



Scattered cirrus and cirro-stratus frequently mark or 

 indicate the path to be followed by summer showers. Some- 

 times cirrus merged with alto-stratus do the same. Alto- 

 cumulus and the higher type of strato cumulus often mark 

 the path of showers to follow. That is. one may quite often 

 know from these clouds that showers moving from the west 

 will pass to north of his locality within 4 to 10 hours ; or that 

 they will first develop to the north or northwest and will 

 later overspread his vicinity : or that they are likely to occur 

 only to the southeast of him. Alto cumulus in early morning, 

 moving from west or southwest over or near the zenith, and 

 unaccompanied by approaching storm clouds, indicate thun- 

 der showers the following mid-afternoon or evening. 



There is one combination and sequence of cirrus and 

 alto-stratus in afternoon and early evening that indicates rain 

 with thunder for the following morning or early forenoon 

 nine times out of ten. This combination has been used suc- 

 cessfully in evening to predict rain for the following morn- 

 ing when even the P. M. weather map of the day did not show 

 any storm approaching or developing. 



In a similar manner clouds often enable one to know 

 whether an approaching shower is likely to be heavy or 

 light; or when rain now in progress will cease; or whether at 

 the end of one shower another is soon to follow ; and num- 

 erous other features of interest or value. 



The foregoing illustrates what may be done by cloud 

 study. The rules given will apply in the northern half of 

 Illinois and the most of Iowa, and in most of the surround- 

 ing states with probably slight modifications. For other 

 sections of middle and eastern United States further changes 

 would doubtless be required, but the same methods could be 

 used to advantage. 



To use these suggestions it is of course necessary to be 

 acquainted with the standard classification of clouds. A con- 

 siderable fund of personal observations and experience is also 

 essential to familiarize one with the cloud types mentioned, 

 as these can not always be accurately recognized from a 

 mere verbal description. 



