Evening star. [volume] (Washington, D.C.) 1854-1972, 1901-05-01
PROLONGED HOT WEATHER..
4 conditions. Which Produce waves a""
Extend Them.

..tI,- Waves Conditions Which Produce
Them and Their Effect on Agriculture Is
the title Of an article by Alvin L. Bur
rows OF the weather bureau. written lof
n,7hlfration in the Agricultural Year Book
which is in press He reviews weather con-
rii1fnrs during the hot waves OF september
1s,5, and Of August and September, 1900
Of general weather conditions 10 b. eX-
pe.r-I during hot waves, Mr. Burrows
SAYS:
..T-gi,. location Of the center of extreme
beat viii generally be fo"nd on ite h1L lL1i
,.r!. and western outskirts Of the nigh pres
sur. The. distribution OF pressure Will be
.,bu..t such as has been described Inc
l,1 st-yfty Of the hot wave seems 10 DEPEND
tsr,,r u Stacking up in the general clrcula-
zion Aside from the direct heating from
liz. sun dynamic heating and lack OF radla-
ZION have an important influence III hlalil
rainiu. the temperature at an abnormal
liz we Al such times the atmosphere pc
comes heated 10 much greater altitude
fr-iu usual the heat being retained al nSht
I,y conditions explained further on in this
4~t..i.. The air which flows eastward
across The Rocky mountains and into the
},vy has been bcrrft of its moisture, and on
descending into the lowlands gains heat
dyramiyaIIy. The air eTnanatlng from the
high III the southeast goes through much
IN same. process The clear days warm up
the atmosphere and a night the radiation
is CRAFTY impedcd.
ON II the peculiar features of the hot
wave. ueriYl Is that. understanding the
,.g..ti,s~ nights ordinarily favorable for
recitation. the air retains its heat in a
Iuauu~r that seems little short OF remark
able For some reason the normal radla-
t5au is greatly impcfled and almost totally
s..~urIdrd. The exact cause of this cessd-
tipa 81 normal action has not been den
uit,iF determined. although the investiga-
lions Of Prof Very have shed much new
Iieug uu the subject. In his report on at
IuoSr!trric radiation recently published by
tie weather bureau, he states that this
coalition Is brought about by the gradual
accumulation of water vdpor in the upper
air. which. although u0t sufficient to form
clouds is Of such natur" as TO transmit
I'll fasS " the sun with greater re&tdl-
ness tEIu the reflected rays from the cart n
This hts the effect Of aCcumulating the
heat i'm the lower strata, causing the night
temperature To be unseas"nably high At
s!eH times the elimination of the daily
range Of temperature with clear sky. as
sattgatIou approaches is probably due 10
CrdHg- in the quality OF aqueous absorb
Ji1i. and also IL the increase of water va
por and its ascent T. exceptional heights
Ia considerable quantity. whereby the es-
cap Of radiation is imprGed by the strong
aqueous absorption of the infra-red rays
not FAR from the point where the maximum
energy In the radiation from bodies at ordi-
nary temperature resides
To sum up. II may be said that, with tbs
present fragmentary knowledge of the
basic cause of meteorological changes. We
hot wave the eastward circulation OF
the atmosphere, both upper and lower, i:
for the time being almost totally suspend
ed, and that radiation is al the same tim.
at minimum careful study of tn.
weather charts covering such periods lead
to the belief that it is quite practicable
to forecast high temperatures for periot
OF from four to five days, but predictions
for longer time are. for the present a
least. the merest guesswork and not enti
tied to credence.