The Relation of Ice Storms to Trees. 



By John W. Harshberger, Ph. D. 



The year 1902 was noted for two exceptionally destruc- 

 tive ice storms that visited the region lying contiguous 

 to Philadelphia. One of these storms occurred on Friday, 

 February 21st, and the other on Saturday, December 13th. 

 The storm of February 21st was accompanied by high winds 

 and did an irreparable damage to the fruit, forest and 

 shade trees. The storm of December was noted for the 

 larger amount of ice formed, but the damage was not so 

 great, because there was very little wind to break ofif the 

 limbs that were weighted down with the ice. 



Meteorologically speaking, regions of strongly variable 

 temperature are subject to occasional winter storms in which 

 the precipitation, occurring as rain, freezes as soon as it 

 touches any solid body, such as the branches of trees, tele- 

 graph wires or the ground. This happens when the ground 

 and the lower air have been made excessively cold during a 

 spell of clear anticyclonic weather, when a moist upper cur- 

 rent in advance of an approaching cyclone' brings clouds 

 and rain. New England is particularly subject to such 

 storms and in the winter of 1886, three ice storms occurred 

 in January and February, but this was exceptional. They 

 were all accompanied by nortiieast winds with surface tem- 

 perature at or a little above freezing, while slightly higher 

 temperatures prevailed on Mount Washington.^ Although 



' A cyclone, in the meteorologic sense, is an area of low pressure with 

 inflowing spiral winds, seldom of destructive strength on land. 

 ' Davis, W. M., Elementary Meteorology, p. 294, 1894. 



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