338 MONTHLY WEATHER REVIEW. JUNE, 1920
An interesting detail concerning the well-known and much-described sea fogs of San Francisco Bay came again to the writer’s attention not lon p. The rela-
tions of land and water as they affect t e behavior of the fog west of the bay are easily understood from the map herewith. Under the impetus OF t h e y l i n g west- southwest wind, when conditions outsi e on the Pacific Ocean are favorable, the fo often flows over the two
ness of the San Francisco sunmer) and streams through the Golden Gate. Seen from the campus of the Univer- sity of California, its; spreading front entering the bay looks not unlike the front of a distant glacier. Quite commonly this front is for some hours kept, “burned off” over the inner shores of the peninsulas and the relatively warm watera of the bay, leavin the broad e s anse of
Hills clear and sunn . But occasionally the following
ba and plain still remaining clear. &q$nning somewhere near Goat Island and esknding northward toward the shore, a fog bank forms, of con- siderable density though never equaling that of the thirk ocean fog. Its south end i s almost always wispy and ragged, and its north end usually trails of€ in the wind u the plain to the northern part of the Berkele Hills.
east of it over the slo ing lain. rst t ou h t seem all against the
sea air in its passage over the relatively warm waters of the bay is warmed enough for the fog in it to evaporate. The fog reforms, however, over the eastern art of the
hence on sunny days is warmer than the dee er water on
already cool incoming air as it crosses this belt of warmish water. It is not likely that the conditions of cold air over water that is warmer are here even approsimated- the fog can scarcely come from that source. Further- more, this fog bank is a quickirm-ing affair, often reaching one to two or three hun red feet in thickness within a few minutes after its beginnin . And there is
not, except in one restricted area, any feight of land at the shore which would cause cloud formation by forcing the air to rise; such, however, is very commonly the case
on a low hill (300 feet) at the edge of the plain in t,he northern part of the fog area. The following esplanation niay be the correct. one.
Because of its passage over the belt of shallow, warmish water, the relative humidity of the air is soniewhat in-
peninsulas (accounting, there 5 y for the proverbial chilli-
water and the adjacent plain a t % t e foot of the gerkeley
variant on thesexon 2 itions occur, the major part of the
&em is clear air west of it over the bay, and c r ear air
bay, in spite of the fact that the water is very s R allow? and
the west. There can be little, if any, ch s ling of the
The conditions a t formation of fog in that particu Rq ar zone. The fog-laden
creased as compared to the relative humidity over the cooler water of the bay. Therefore, only a very slight further cooling may be necessary to cause condensation. But, a run over the land would have the opposite effect of reducing the relative humidity. Now, over the plain
on sunny days convection currents are active, and they may be strong enough to function as a sort of buffer against and over which the cooler and moister air is forced to rise, thc convection currents being at the same time weak and dry enough to cause of themselves little or no cloud forma- tion. Concleilsation would take place then only on the western edge of the convection area, where the slight lift- ing of the cot$ and very humic1 air causes the necessary further reduction in tem erature. The level of condensa- tion is only a few yards a E ove the house tops. Usually the air over the plain is clear, thou h occasionally the con-
toward the hills on their way t,o merge with the major cloud mass about the summitss.
. In correspondence with the writer, Dr. C. F. Brooks suggests a possible additional cause for the condensation observed, name1 that the somewhat warmer air along the shore belt of%iallow water, movin relatively slowly
densation point by the admixture of faster-moving air from the west. This cause ma7 well operate in conjunc- tion with the convection barrier to produce the effect. As may be seen from the sketch, the more northerly part of the fog belt, trailing off over the land, is in a position favorable to such action. But the beginning point of the
under the influence of this land-induce resumably friction. The not belt is somewhat offshore, and hence
following is offered as a possible esplanation of the con- densation here. The convection barrier plus friction and misture may cause a flattened wedge-shape mass of slightly slower-moving air to estend out some distance from the land, and so, to act as a sort of inclined plane up which the oncoming air from the west would move. The result would bc! convection cooling and mixture cool- ing combined, wit.1~ the fog RS a consequence.
As is commonly the case, on the last occasion when this
fog bank formed it ptmistetl until late afternoon, the air over the bay remainin clear and that! over the plain for the most part, clear. 6 i t h the gradud weakening of con- vection the b d e r effect here su ested gave way and the local fog bank disappeared. #longer forced to rise by the convection currents, and mising instead with the warmer air over the plain, the moisture which had before been visible as fog now remained as vapor, until its rise over the higher summits of the hills again caused conden- sation.
vection currents do form smal P rags of cloud drifting
because of friction with the shore, is c 5 illed to the con-
MEASUREMENTS ‘OF SOLAR RADIATION AT MADISON, WIS., WITH THE CALLENDAR PYRHELIOMETER.
By ERIC R. MILLER, Meteorologist.
(Weather Bureau Office, Madison, Wis., Apr. 13,1920.)
SYNOP111S.
Results of observatiom extendi over nine earn are summarized. and data of related phenomena ofiuration of Znght sunshine and of cloudinese are ’ven. A midsummer depression in the annual march of midday n o d i n t e n s i t y is aecribed to a maximum of haze at that time, due in turn to the increased evaporation of water and stronger convec- tion. Spring and autumn depreseions in the annual march of sun and sky radiation upon a hOn7mtal surface are ex lained aa arisin from the double I118x1113um in the annual march of Lquency of ‘’ &?orado lowe.” The suggestion is offered that this double maximum is produc- ed by the most efficient cooperation at intermediate seasons of the sta- tionary barometric depression in Northern Mexico and the eastward drift of the atmmphere, the annual owillations of which are in opposite phases.
No. 9864 has been used throughout the series of observa- tions. This is the four- id t pe, already described and illustrated b Kimball (5 d o different recorders have been used, 8dendar Recorder No. 143 was used from
JUNE, 1920. MONTHLY WEATHER REVIEW. 339
April 3, 1911 to July 17, 1912, Recorder No. 333 from that date to the present time. E;cposure.-The Tece;iver is exposed on top of the ther- mometer shelter of the United States Weather Bureau oflice, on North Hall, University of Wisconsin, a building on the upper cam us, on a hill rising abruptly from the
or 308 meters, above sea-level, 163 feet above the surface of Lake Mendota, 71 feet above the ground, and 13 feet above the roof. The horizon of the instrument is free except to. the southwest, where the low, yramidal roof of
The dome of University Hall, which burned on the morn- ing of October 10, 1916 rose to 11’ and a fla taff on the
dome to 15O, between 6. 61’ W. add S. 67O # The sun paased behind the dome each afternoon from January 1s
to February 21, and from October 31 to November 25 each
south shore of La f e Mendota. Its altitude is 1,009 feet,
University Hall rises to a oint 4O, and t R e chimney of the university heating plant P arther on, 5O above the horizon.
Brdzc.ction. -fnetm.-Prof. Callendar su plied with the
centinieter of exposed surface, per minute, per scale division of 4.0 mm. on the aper sup lied by the makers. Paper ruled in inches ant! tenths R as been used with register No. 322, and for this the equivalent factor.is
1 inch to 0.3505 calories, etc. The time-scale of this recorder has been changed to make it more open, a scale of 0.797 inch to the hour bein used. The instrumental factor has been utilized in r d n g scales on brass (1) to read calories er minute, divided to hundredths of calories, each 2 ivision being 0.725 nun., and (2) to read calories per hour, divided to calories, each division 1.208
calories. These scales enable the sheets to be read off very rapidly. Instiwmen.taZ errors.-Although the Callendar p rheli-
realization of its purpose is frustrated by a variety of
instrument a factor of 0.0552 gram-c &p orie per square
ometer is an invaluable aid to the meteorologist, t i e full
FIG. I.-Average and maximum intensities of radiation at Madison, Wis.
year. The maximum effect of this artificial eclipse of
the sun is estimated to have been a loss of less than a s m d calorie a day on clear days. The atmosphere of Madison
is generally free from dense smoke, since the city has few manufacturing plants, and these are all 3 or 3 miles east of the station. In winter there is often light smoke from domestic heating and cooking, and occmonally in very cold weather smoke or condensed steam from the univer-
sity heating lant and from locomotives passes over the sun, especi as y when the wind is southwest. The ori- ention of the receiver which has an important effect on ita indications, is with the black grids in the meridian, north and south, while the bright, compensating grids lie
east and west.
physical conditions, some of .which can probably not be overcome. Five or six of these sources of instrumental error are discussed in an accompanying paper on the “Characteristics of the Callendar p.yrhehometer.” The data given in the present paper have not been co-rrected for error, partly in order that the results may be com- pared with similar observations elsewhere and partly because the total error is unknown under some circum- stances. Resu.lts of re.&trution.-The sums and means o’f sun and sky radiation upon a horizontal surface are tabu- lated by hours, clays, months, and years, and repre- sented in curves a t the end of this DaDer. The most
1 This SEVIEW, pp. 344-347.
340 MONTHLY WEATHER REVIEW. JUNE, 1920
January. ................................... February.. ......................... March. .. .\. ......................... A ~r i l . .............................. Kay.. ............................... June-.?. ............................. July ................................. Au t ............................. Bep%ber.. ........................ October ............................
important factors in causing variation of these data are, naturally, the daily and annual changfs in the relation of-the earth to the sun by rotation on Its axis and revo- lution in its orbit. Superimposed u on these normal
the weather. Of these, two phenomena deserve especlal attention, namely, the annual march of atmospheric transparency and the annual march of storminess. Annual march sf trans arpncy.-The transparency of
%e regarded as caused by solid particles, as c ust
at much less than the saturation vapor pressure for n plane .surface of water. Aside from large accidental variations of. the dust content following volcanic erup- tions, there. is a fairly regular annual niarch rangin- from a masimum in sunmier, when the soil is dry an8 dusty and there is active convection to carry iust ai!d water va or hi h into the atmosphere, to a minimuni in
vailing vertical movement i i downward in the continen tal anticyclone. The annual niarch of transparency is most evident in the observations of the direct solar radiation with the Marvin pyrheliometer. The values of the coefficient of transmission in Table 1 are derived from seven years’ observations wjth this mstrumei!t. Curve IV, figure 1 ,
giving the maximum noon intenslty of direct solar raclia- tion observed with the Marvin p.ylheliometer, while ‘affected by annual changes in the earth’s radius vector and in the length of the path of the solar rays through this atmos here a t i?oon, shows the preponderatmg
variations of “solar climate” are all t R e irregularities of
the atmos here is reduce 8 by haze and by water va or.
P and liquid droplets of water, which, can esist
winter w i f en t e ground is snow covered, ancl. the pre-
influence o P atmospheric absorption.
TABLE l.-Ahnoapherke tmnnnission eoefl&&t, a, for Jfadiaon, Wi8.
[Frmn seven years of oh!eryat.ion qlth the Marvin pyrheliometer, by comaarkon of the intensities of solar radlatlon at different altltudes of the sun on the same dry. Data
furnished hy Dr. H. H . Iilmball.]
-
1.5
a MI 8% .is1
i.l4 i50
io0
.i34 .i52
.i39
1 N h i n g ohservations. I Afternoon observation%.
2.0 2.5
I
1.5
0.s2.l 0.69
.Si . SI9 ........ .R1 .%.I 0 .w 800 .fill .i66. l i e 1 .761 .i4$
.i i O .i95 .i l 4 .W .i51 .R%
.i.% .MI .713
.771 .is3 .740
.i t % ,792 ......... . .WI) ..xu ....... .S O
-____..--
Air mass.
I-
Month. l- Air mass.
2.0 2.5
................ 0.813
.si .w .i2R
.is .ill
.730 .i 5 i i71
................ ................ Rangeor calories.
i51-m. 701-i.50. 651-7110.. tiOl-65fl.
ss1-600.
501-550. 451-Mo.
401-4.5n.
8 S l -m ..
30140..
251300..
201-250.. 151-ZW3..
101-150.. 51-100. ._ 1-60.....
Jan. Feb. Mar. Apr.
I ! ....... ....... ...... ....... ....... ....... ....... ....... ...... ... 13
?S 21 19 15
9
n. y19
. S%
. (47
.A l l
.73x .id7
. i31 .i36
.in . 7%
. Kc
Ai@.
1
s 1s M 0
9
9
6
(1
4
The annual of stominess.4urve 11, figure 1,
the aver Q daily amounts of sun ancl sky radiation on a
Ma , and June, and another lesser depression in August an$ September. These depressions occur before and after the time of lowest transmission coefficient, and are therefore not due to atmospheric haze. It will be noted that these depressions do not a ear in curve I, tigure 1,
the maximum recorded sums otxaily radiation from sun and sky oh a horizontal sul-face as they would if due t:, variations in transparenc . That the sprin and autumn
is clearly shown by the frequency distiibution of t e daily sums of radiation. For illustration use is here made of the ‘‘method of
qercentiles” which is expla.ined by Yule, Theory of Statistics, page 150, in the following words:
horizonta T surface, shows a marked depression in April,
K
depressions are due fo a 9 arger proportion o 5 cloudy da s
Sept. Oet. Nov. Dpe.
--Ap-
............................. ............................. ....................... ........................ 2 .................. 5 .................. 14 ................ 3 1 ........... 13 14 ............ 10 20 ............ i 19 18 ...... R Y ?3 12
If the values of the variable be ran d in order of magnitude and a value P of the variable be deter+ec$such that a percentage p of the total frequency lies below i t and 1Wp above, then P is termed a per- centile. The deciles, or values of the variable which divide the fre- quency into 10 equal parts form a natural and convenient series of percentiles to use.
Jnue.
--
12 1;
9 12
10
FIQ. 2 .y A n n u a l e of the decll9 of the Ire uency distributmn of daily sun md sky radiation s h o w p e r cloudmeas in spr?ng by occur- of large proportion of days lo 16wer part o scale of intensity.
I n figure 2 the sanie decile in the successive months of the year lies on one line, so that the diagram shows the annual march of the deciles of the frequency distribution
of the daily amounts of sun and sky radiation. It is obvious that the lower deciles are greatly depressed in spring. .The reason for this is the occurrence of a lar e number of days with small totals of radiation. T i e customary form of frequency table does not show this phenomenon, but i t does show that the clear day is the “mode.” (Table 2).
TABLE 2.-Freqi~et~cy distribution of daily mma o radiation froin SIIIL
and sky iipon a horizontal aitrface, at Madison. f ia., April, 1911, io
March, 1919, h c .
[The prlncipal mode in italics.]
--
July.
-
............ 3 4 12
2.5
17 11
7
S 6
6 6
5 3
8 4
4 1
........... ........... ........... ...... ...... ...... 2 13
............
3
fi
15
1.J 11
.... 1 4
10 15
12 6
5 i n
Percentage oIdays.
-
May.
1 6 13
12
Y 10
4
9
s
5
8
6
8
4 2 1
-
-
The cause of the autumn depressions in the
in the region of
annual march of mum in the Madison.
to be a double maxi-
The annual march of storminess for each 5’
JUNE, 1920. MONTHLY WEATHER REVIEW. 341
Apr. I May.
---
4 1 2
17 13
25 15
60 60
4R 4 i
..... 2
zone from latitude 25 to latitude 55", between lon i- of different areas to form storms. While the contindnt tudes 85' and go', is shown in Table 3, which are fe- cools in winter the Gulf of Mexico remains warm, and rived from data in the monograph of Bowie and thereby comes to be a soiirce of cyclonic storms at that Weightman (4). season. A frequent type of storm experienced in Wis- consin is that from the southwest, designated by Bowie
LOW is the only grou of storms in their Table 1 having a
double maximum of P requencg in spring and fall.
TABLE 3.--Nztnibe:of LOWS that WO88ed 70478. 85°-900 in the 9 1 !/fQr8,
[Mnuima in Italics.]
and Weightman the ''Colorado mw." The Colorado 1892-1912.
- -- - - -_ I I I I I 4 I I
June
6
17
2i
.IS
3
July. Aug. Sept. Oet.
2 3 9 1 5
3 4 10 9
33 30 27 [ 21
6.1 6.S 60 b;?
151 6 111 10
--.--I ' I '
---
8 1 0 9
Nor. nec.
5 13
15 30
51 3!l
62 5s
6 ) 5
5 2 9
--
25-30.....
.3&35.....
:I 5-40.....
40-45'. .. 15-50.....
50-55*.-.
16
30
28
35
57
8
.. ... __ . .. .- . - .. . - -_ - BIG. 3 -Anniial march of frequency of Colorado 10-m of tatmasphmc pmsure at Phapnix Ani. (inverted ), and of mean velorltim of cent& of low pressure, showing maxim; of Colorado lows ins rlnp and autumn, when the Mexican center of low ressure, and the westerly drift ofthe atmosphere mwt eflectirely cooperate to pro%uce moving
storms.
The cause of the double annual period of the Colorado
LOW appears to be the effective cooperation in spring and autumn only of two storm-producing factors that flue-
1 Madison in thla zone, Lat. 43" 05'. ' * Data incornplcte.
Madison appears to lie ill a transitioll between tile northern border with its summer maximum of storniiness and the southern and central States with their winter maimurn. This phenomenon is less probably a shifting of the storm belts than an annual c.hange in the tendency
16
34
41
3 i
F!G. 4.-Pyrhelisopleth, for Madison, Wis.
4
2?.
32
34
342 MONTHLY WEATHER REVIEW. JUNE, 1920
’ /.
A. Mean barometer Phoenix, A+ .__. B. Mean veloeit of
e ___. !a?- C. Number of Colo-
1912 .........__._.
centel$ of low
rado LOWE, 189%
tuate annually in opposite phases. These are the low-
pressure area of the southwestern United States and northern Mexico and the s eed of the prevailing westerlies over the United States. &he tendency of the “Mesican center of action” ‘to form R storm is greatest when the This “cyclonicityJJ is represented in igure 3 by inverting the annual niarch of atmospheric pressure at Phoeniz,‘ Ariz. The force required to move a cyclone from Axikona eastward must be supplied by the eastward drift of the atmos here. This estends farthest south over the region, “folEwin .the sun,” and has the eateat velocity in midwinter. gepresentin (Fig. 3) the
from von Herrmann’s tables (51, it is obvious that while each factor by itself is not at its maximum the coopera- tive &ect is at a maximum in March and October, when the maxima appear in the curve of annual march of
rasure is lowest.
Ktter by the mean velocities of centers of f ow pressure,
Jan. Feb. Mar. Apr. my. June July. Aug. Bept. Oct. Nw. Dec.
---------_.--
28x4Q0.8190.7580.7~0.8460.6170.8830.67~0.6s40.7~~0.~0.~
34.8 34.8 31.6 28.9 24.3 24.0 24.4 24.6 24.8 27.4 30.7 34.9
30 31 39 1 30 25 19 20 14 36 23 23
“Colorado LOW~T”
Construction of tho: tables of da.fu.-The arithmetical mean of the hocrly and daily’suii and sky radiation for each month is the basis of Table 4. A similar table, but for each “decade” (1-10, 11-20, and 21-end) of each month forms the basis of figure 4. Table 4 in- cludes one year more of reservations than fi ure 4.
clouds in the sky, obtained graphically, is the basis of Table 5. Clear sky for a full hour was the criterion for selecting data to be included, even though other hours on the same day were cloudy. The daily s u m from Tables 4 and 5 are repeated in columns 1 and 2 of Table 6. In columns 3, 4, and 5 of this table appear the maximum total recorded in any one day, for each of the three “decades.” Similar data but for one year less form the basis of Curve I, figure 1. The monthly sums from which the data of columns 1 and
2 were derived appear in columns 6 and 7. The duration of bright sunshne, in percentage of the possible, as recorded with the Marvin mercurial sunshine recorder, during the years April, 191 1 to March, 1930, inc., a pear in column 8. In column 9 is ven the mean cloud!ness,
hourly personal observations.
The mean hourly total for hours when t E ere were no
during daylight hours, for t f e same period, from bi-
1 Plgure 3 ia based on the following data:
A-Blgelow, F. H. Barometry of the United States. Report of the Chlef of the
B -V ~ pwmimn, Moi-miuv$mnrtrrr REVIEW I, 189-171. C-Borne and Weightman, MONTHLY WEATHER ~E V I E W . SUPPLEWENT No. 1, 1914.
Weather Bureau 19oo-01 vol 2 557.
Table 1.
The radiation-history of Madison for nine years is given in Table 7, where the monthly and annual totals
of radiation in gram calories appear month by month and year by year for the entire eriod.
in terms of the nine-year mean has been calculated. ’ The most noteworthy features of this table are the long- continued deficiency in the summer of 1915, which was also extraordinarily wet, and cold, and the much eater
F e b r u e than for the rest of the year.
111 order to show the. excesses and deficiencies t f e percentage ,of each month
variability of the data for the months Novem f er to
MOT.
1
a
4
a
f b
7
a
e
10
I1
NOON
1
P
a
4
a
$b
7
m
e
10
I I
MOT.
Acknowldgment.-Figres 1 and 4 were prepared in the Solar Radiation Investi ation Section, United States Weather Bureau, under t fl e direction of Prof. H. H. Kimball.
REFERENCES.
I . KIMBALL. H. H. and MILLER, E. R. Solar Radiation inkmitiee at Madison, Wis. Bulletin of the Mount Weather Observatory, Vol. 5,
2. ZIPBALL, H. H. and MILLER, E. R. The total radiation received on a horizontal surface from the sun and sky at Madison. Wis.. April. 1911 to March, 1916.’ MONTHLY WEATHER REVIEW, April, 1916,44: 180-181. 3. KIMBALL, H. H. Total radiation received on a horizontal surface from sun and sky at Mount Weather, Va. MONTHLY WEATHER RE-
VIEW August, 1914, 42: 474-437. 4. ~O W I E , E. H. and WEIGHTIAN? R. H. Types of storme of the United States and their ave movements. MONTHLY WEATHER REVIEW, SUPPLEMENT No. l,%in@on, 1914. 5. VON HEERMANN, C. F. The velocity of centers of high and low pressure in the United States. MONTHLY WEATHER REVIEW, April,
1912. p. 173-183.
1907,35: 169-171.
MONTHLY WEATHER REVIEW.
17.2 25.6 36.3 41.3 46.3 48.8
43.9 36.2 25.2 16.9 13.7
51.0
JUNE, 1920.
24.6 33.7 43.7 48.8 52.9 55.3
51.8 43.5 32.3 23.5 19.7
5 8 2
343
January. ................................. February. ................................. March.. ................................... A ril.... .................................. b& ............................... June ............................... July.. ............................. August.. .................................. September .................................. October.. ................................. November. December..
TABLE 4.-iUean hourly, and duily intensity, of the vertical component of sun and 8l.3 r&tiOn, at Hadison, WG., gnrm cal&. dpr., 1911, to Mar., 1920, inc.
I I
.I.. .............. ,. ....... 0.3
1""iS' s.4
3.0
0.2 4.6 14.6 0.91 7.4 18.6
0.3 5.0
j ........ 0.7
............................................... ..............................................
For the hour, apparent solar time, ending at-
1.5 5.3 12.6
20.2 26.0 30.2 29.5 22.7 15.4 6.6 2.0 0.5
8.5 15.1 25.2 32.0 37.0 40.5 41.7 33.9 26.6 16.0 8.9 5.8
2 1 7.6 1 2 .8 ' 22.2 23.4
10.4 5.2
.a
18.3
6 7 8
--- ....................... ................ ................ 2.3 ........ 8.5 1.0 9.7 1.7
2 0 ........ 0.7 ........
LO 0.9
................ ....................... .......................
(Noon.11
47.3 R2.3 75.1 w .9 83.3 $2.0
78.0
65.3 48.7 41.6
34.9
71.8
17.3 60.4 74.3 79.9 m.0 820 77.3
63.0 48.8 40.9 35.3
69.8
39.1 54.2 67.5 72.9 77.0 77.7 71.8 64.0 58.2 43.3 35.6 29.4
30.0 44.4 58.4 63.9 68.9
69.0 64.2
55.6
48.3 33.3 26.2 20.4
15.6 28.2 42.1 48.1
54.0
51.5 4 2 2 35.2 20.2 13.5 R 8
an
3.9 11.6 23.6 30.4 38.5
35.1 24.5 17.4 5.6 3.3 2.0
39.7
4pril: .....................................
July ................................ AugusL.. .................................. bptembcr ................................. Oetobr.. ... -6.. .................................. Nowmber.. December
M a y .......,...... ................. June ...............................
....................................... .........................................
2.1 ! 13.Y 1.0 S.9 26.2 1.5 in:s I 5 .p
.8
.7 6.2
-1 .2
I. .......
I --- .. -. -1
C.re.it-t recorded dsily radlstion.
1"-10" ll"-?o" ?l"-end.
Mean doily. . -
- Month.
Alldala. 2% Amount. Date. Year. Amount. Date. Year. Amount. Date. Year.
~
_--___- ~--~~--
.................... 31 1918 January 163.3 273.3 259 9 1912 289 19 1912 3 3 Fehm-y 243.9 .lM.1 ;I&? 9 1912 394 20 1917 455
March ...................... 342.0 545.7 503 7 19m 534 16 1918 6f.M 29 3913 A ~d l ....................... 504.4 63.0 6fl6 7 1911 Bs? 20 1911 m 24 1911 l d ~~ ........................ 467.4 y 3 .a 743 3 1911 78'2 11 1916 755 30 1915
........................ 9 1913 769 16 1917 770
Aupust ..................... 44Y.9 55!.5 711 1 1913 818 13 1916 649 29 1911 Lptemher .................. 311.4 470.3 557 1 1915 859 490 21 1915
29 1912 ...................
28 1911 June 519.6 r3?.7 765 July ........................ 539.4 fi57.8 7s1 4 1917 7 8 12 1911 788 31 1911
October .................... 230.7 305.2 4.56 2 1913 390 11 1914 ! 3-27 27 1914 November .................. 155.R 2440.0 p34 2 1911 253 14 1916 232 22 1914
19 1911
December .................. 127.8 193.1 L30 3 1911 2% 15
I
1919 j 225 30 1014
1
a6ontllly amounts. DW8- tion of
SullSlliTle
Alldays.
Per e&. 7 496 45
2% 10'258 52 10'602 15'3% 57 12'131 18:840 54 14:M 21 950 58
13'917 U'210 64 10'242 14'110 58
3,944 5,988
63 15,581 21'853 16 415 21'227 71
7'195 10'704 48 4:752 7:199 41 38
10 I 11
....................... a 5 ................ 3.9 0.0 ........ a 4 1.6 ........ 13.4 4.6 0.2 16.7 6.4 1.0 16.5 5.9 0.6 11.1 2.8 ........ 4.2 0.3 ........ 0.8 ................ ....................... .......I ........ I ........ I I I I . I __- I I I
TABLE 5.-Average hourly m d daily intmaity of the cwtical cnrnponent of radiation from sun and 8ky under cbudk8s e&& gram cab&.
For the hour, apparent solar tlme, ending at-
-
11 9 1
-I
2 1 3 1
40.3 55." 07.4
77.7 7 2 A 66.3 BO. 9 41.3 36. s 31.3
ti: :
23.7 42.2 57.0
71.0 71.7 65.7 5s. 8 51.3 33.4
90. R
rA. s
?a. 1
I
3.0 10.4 3 .3 31. i 53.3 44.3
3R. 5
2% 0 20. s 6.7 2 9
17.1
42.0
51.0 59.0 5s. 7 53.0 43.9 37.1 20.5 13. 1
9. I
TABLE f~.--S~itti~nar!~ oJ'n1t.m~ mnd extre)ne8 ofradktkn, etc., by months.
ldsen cloudi-
da$&t h m .
Per mu. 86 64 63 65 63 61
51 57 61 65 67
m
' TABLE 7.-Monthly and annual 81mi.8. and ptwmtage8 of thr 9-gt-n~ n i e m , OJ the sun a d sky ra&tkn upon a ho&ontal -face at X a k , Win., froni April, 1911, to March, 1920. r')aclrisl:ar, in gram calorie3 per squme mtinutm per minute.
Apr.
11,472 95 12,663 104 13,380 110 12,213 101 13,069 108 12, 737 105 11,730 97 ll,W 98 10,042 83
13,131
-
........ ........
June.
16,153 104 16,881 108 17,704 114 15,193 97 14,605 92 15,673 101 13,630 87 15,681 101 14t 779 93
1% 591
-
........ ........
July. Ang.
-
14,072 101 13,580
13,028 93 14,128 102 12,884 93 14,516 104 14,239 102 13,711 99 15,297 110
13,917
96
........ ........
a p t . Oct.
-
%! 7,932 110
7,380 103 7, cno 98
7,934 110
7,793 108 6,400 88
7,
6s
........ ........ 7,195
DW.
4,217 107
4 ,m 102 3,717 94
110 3,619 89
4,180 108
4,342 110
-
E
2, F
........ ........ 3,944
Nw.
4,551 96 5,137 108 4,218 89
5 ,m 119 4,947 104 4,831 102 4,318 91 4,895 92 4,810 101
......... ......... 4,752
YW.
laS12l4
122,866
ia 122,818
ia la, 767 102 11r,Oe? 94 lU, 072 lOa 122, rn io1
' 1 m ,m
116,847
12l,246
lo1
99
96
......... .........
-
Mar.
......... ......... 1'2,006 113 10,008 94
11,883 112 10, 272 97 10,031 95 11,446 108 9,739 92 10,175 96
lo, 6oa
9n F
May.
15,843 108 11,948 83 13, w)6
96 16,238 112 12, 494 88 15,024 104
la, m 110 14,194 98 14,752 102
14,489
......... .........
YW.
l 7 .m 105 15,623 95 17,413 106 17,417 108 13,273 81 17,872 108 16,736 102 16,187 99 16,014 98
16,415
......... .........
IO, 588
lo, 001
9,
11,060 108 9,429 92
lo, 4a3 102
lo, s6!a 103 10,246 100
9,970
97
lo, 242
104
98
......... .........
.. .. ....... .......
6, * 101
7,422 1M 5,062 73 7,392 106 8,147 118 7,146 io3 5,926 86 6,616 96
6,905
7s E
lorles ............... ................ 1911 Per cent. ............. .............. ............. ..............
.............. ........... .............. ........... ................ ............. ............... ............ .............. .............. ............ ............ .............. ............ ............ .............. ...........
1912..
1913..
1914..
1915..
1916
1917.
1918..
1919..
1 m ..
Mean. .............
......... ......... 6,297 124 4,651
'
92 3,196
a
4,117 81 6,108
im 5,982 11s 4,878 96
41 %
5,063 /I .I I
4829--20---3