8 OC EF Dutton—Hfect of a warmer Climate upon Glaciers. 
e than a simple ratio. Inasmuch as it can be made intel- 
ligible only by the use of an algebraic expression, the analysis 
of it is given in the appended note.* The general result of 
that analysis is that when air moves from a warmer to a colder 
place, where it is cooled Zeck radiation, the amount of cooling 
(by sivaer ade simply) over any given area, does not increase 
in the same ratio as fe Heoloae of the wind, but in a ratio 
Which itself diminishes rapidly as the velocity increases. 
(15.) We have thus examined the essential features of the 
first two factors which determine the rate of precipitation with 
reference to the changes they would probably undergo if the 
earth’s climates became warmer. These changes we find to be 
very small for any increase of warmth which would be postu- 
lated. So rai are they that hereafter they will be considered 
as unimporta 
(16.) ‘The third factor which determines the rate of precipi- 
tation depends for its value upon the temperature at which the 
cooling of saturated air begins. It is by far the most impor- 
tant factor of the three. Its value is directly proportional to _ 
the maximum density of water vapor considered as a function 
of temperature, and it is well known that this density increases 
with the temperature, in a very rapid ratio. A roughly ap- 
proximate idea of it may be derived from the fact that at such 
temperatures as we are most concerned with, this density, or, 
what is equivalent, the so-called capacity of air for moisture, is 
about doubled for an increase of 10° C. in the temperature of 
us consider an area of unit width over which air is passing. 
that while it is passing, some cause, the nature of which need not be specified, 
t som 
e 
the air over sa tem mperature at which Sonera and absorption would become 
instantaneous ltd of the Seeger eg as the s, this potential is con- 
stantly diminishing. Let then P be the initial een es the potential when vend 
air first reaches the supposed area and let ‘ be its value after any time 7, durin 
its passage over it. Then the change dp in the value of the Seren dutttig 
any time dé (taken so small that he its ateticn p may be as sen- 
sibly constant), is expressed by the —dp=pdt. Integrating this 9 petweet 
the values P and p for the seal ¢ nd cathe the corresponding values of 0 
and ¢ for the time, we have log p—log P=log Oe t, and gd Now the 
Leg cooling during the time ¢ of see unit volume of the air is equal to 
of potential; that is, P—p=P(l—e~). If ¢ be taken as the whole time pe 
passing, and if v represent the velocity, then ta. Substituting this expression for 
t, we shall have erga rycen of cooling of unit. vanes = by pes while 
passing over area of unit width with the velocity »v the quantity of air 
ere passes is dirootly § proportional to the velocity, and itgne the expres- 
sion by v we obtain the Eq.: Total cooling over given area =Pu(l—e =) ke 
examination of we = shows the general result stated in the text. 
tial P may also be riable and have a slightly increased value oe o a rues 
climate, but any fick teersaonet would of course be very small. 
