FROST 
Grand river, and down stream at the 
average rate of about ten feet per mile; 
so that air drainage is generally good, 
especially in the upper and middle por- 
tions. Also, in the narrow upper end 
mountain and valley and canyon breezes 
are naturally strongest and most effi- 
cient in stirring and warming up the 
air on frosty nights. So that Palisade, 
especially that portion close to the cliffs, 
is the earliest locality and the least like- 
ly to be injured by late spring freezes. 
Outside the Grand valley the orchards 
are generally located on hillsides, slop- 
ing mesas or benches, or in narrow val- 
leys, so that air drainage is usually 
good. For example, the fruit in the 
Paonia section is largely raised on the 
comparatively steep sides of the valley 
of the North Fork of the Gunnison river 
and in the narrow valley bottom, down 
which a wind usually blows during the 
latter part of the night and in the early 
morning, especially during clear weath- 
er. 
Damaging spring temperatures are 
most likely to occur in the district when 
a high-pressure area of considerable en- 
ergy advances in the rear of a low- 
pressure area across this part of the 
state from the northwest. If the high 
has advanced so far that the district 
lies well within it, local air drainage 
produces considerable differences in min- 
imum temperature. But if the district 
lies in the region of circulation between 
the high and the low (particularly if 
the latter be vigorous and lie central 
over the southern part of the eastern 
slope of the Rocky mountains), tem- 
peratures will be more nearly uniform, 
and mountain and valley and canyon 
breezes are likely to be weakened or en- 
tirely counteracted. If the center of the 
high pass some distance north of the 
district, some cloudiness may be ex- 
pected (especially if there be a low over 
Arizona), and temperature fall will be 
retarded. It has been found that there 
is no useful relation from the viewpoint 
of the forecaster, between the evening 
dew-point and the minimum tempera- 
ture the following morning; although 
1021 
the quantity of moisture in the air af- 
fects radiation and hence the fall of 
temperature. The minimum  tempera- 
ture on an April morning at Grand 
Junction 1s usually about five eighths of 
the maximum temperature of the preced- 
ing day. If the air be very clear, still 
and dry, the minimum will be lower 
than the above relation indicates. 
E. S. NICHOLS, 
Local Forecaster, U S Weather Bureau. 
METHODS AND ORGANIZATION IN 
FROST FIGHTING 
P. J. O'GARA. 
Efficiency of Present Methods 
The present methods of frost preven- 
tion by means of fires and smudges, 
using the various types of oil pots and 
heaters, are by no means perfect. Per- 
haps in time we will have some method 
of orchard protection that is better than 
the oil pot now in use. It must be under- 
stood at the outset that the orchardist 
cannot afford to equip his orchard with 
apparatus of too costly a nature; it 
must be simple, or at least easily work- 
able, and not too delicate for practicable 
use. 
The protection ot orchards from frost 
injury is not an experiment in Rogue 
River valley. A perusal of the records 
will show that the experimental stage 
in practical orchard heating has 
passed. A glance over the valley will 
show the large commercial orchards 
equipped with fuel pots for burning 
crude oil, distillate and coal, while oth- 
ers are protected by means of wood, which 
has proven very successful. A commercial 
orchardist who has for the past four 
seasons saved his crop, valued at more 
than $1,000 per acre, is not much in need 
of advice. If the cost of saving his crop 
is well below the maximum it would 
seem that, for him, his method must be 
the best. During the 1911 season of 
frosts the Rogue River valley orchard- 
ists did not experiment. In saving the 
crops from frost injury a safe approxi- 
mation would put the number of fires 
used at fifty thousand. A large number of 
these were fuel pots burning crude oil 
and distillate, but there was also a very 
