] Understanding the Weather 



the magical hand of Jack Frost, but they are of course the result 

 of low temperatures outside, cold enough to chill the indoor air 

 which touches the windowpane. (Storm windows protect the pane 

 and prevent frost from forming on windows.) 



If the chill is sufficient to cause the moisture to condense on the 

 inner surface, frost begins to form. Usually crystals first appear 

 around some tiny irregularity in the glass surface or around a bit 

 of dirt. Often these first crystals continue to grow, and as some 

 of the smaller ones evaporate, their moisture condenses again on 

 the larger crystals. Thus spectacular designs, numerous and in- 

 terestingly varied, are created. 



How TO MAKE FROST PRINTS 



As window frost rarely lingers more than a brief time, 

 children may get a great deal of pleasure from making prints of 

 some of its lovely designs. This may be done with blueprint paper. 

 Sheets of this paper, about twelve inches square, should be kept 

 in a dark place until ready for use. Some morning when the sun 

 is shining brightly though frost prints have not yet melted from 

 the window, take a piece of blueprint paper and quickly attach 

 it with scotch tape to the pane. Press the sensitive side directly 

 against the frost design for two or more minutes. 



The sunlight turns parts of the paper light blue but leaves the 

 pattern of the frost in white. Remove the sheet of paper and im- 

 mediately immerse it in a pan of clear water for a few minutes. 

 Then transfer it to another pan of water to which a tablespoon of 

 peroxide has been added. When the blue part has turned an at- 

 tractive shade, rinse the paper in clear water, then spread it flat 

 to dry. It will make an attractive decoration for any child's room. 



HaiI- 44 Hot-Weather Ice" 



To some people, hail is "hot-weather ice," as it is usually seen 

 during violent summer thunderstorms; it is quite rare in winter- 

 time. Hailstones are formed when raindrops are caught in swiftly 

 uprushing air and are carried high into the cloud tops where they 

 may meet snow crystals. Mixing with the crystals, the raindrops 



