142 MONTHLY WEATHER REVIEW. h H , 1922
ELEVATION AND ALTITUDE.’ ment, anemometer, barometer, or thermometer, for
gin^^^ llse the word e~euatim with reference to the example, was with reference to sea level or ground level. height of an object, usually on the ground, relative to Of come, this uncertainty could only exist a t stations near sea level. It is suggested that a distinction in some level Or ‘Om’ Other hed In usage of the terms elevation and altitude, somewhat akin to that suggested by Dr. H. R. Mill for the terms and aviation, heights above ground in free air are com- monly referred to as altitudees. In meteorology and other
well to limit the use of the term altitude to hei hts above it are sometimes referred to indifferently as elevations or altitudes and the terms are often used efevation to the height of the ground or a fixed interchan erthly. In the table of stations in the reports of the U. 5. meather Bureau, height of ground above se:~ ob’ect On the ground with reference to sea level, Or Some
and height of instruments above ground are both re- ferred to 8s elevations. Such uses of the word elevation near Or Is t’’’ may be. On this basis the height of a meteorological station would be given aa it.s are sometimes confusing. Cases have arisen where i t w&s to ascertain whether the height of an instru- elevation and would be the ground level elevation at the station. The heights of the instruments above ground
1 The -tion by Mr. Horton isan exceUent one. end I mey S T ~S S the hope thst would be =pressed as dtitudes.-Robert E. Horton.
scientific discussions, heights either on t h e ground or mean and average,’ may be deskable. Would it not be
above round at a particular location, and the use o B the
o d er definite datum, the actual point of reference being
it will be uniformly adopted by writers for the REVIEW. In the be inning it would be well for.esch writer to announce on the wasiqn ?t the first use ofeither of.the.tenns “elevetlon” OD “altitude” the seuse in which it is used. The 05cial publleations of the Weather Bureau where the expression “elevation” appears make it clear what reference point is taken 6s e base leVel.-EDITOR.
* cf. Mo. WEATHER REV.. November, lgls~ 46: 514-515.
TEMPERATURES OF THE SOIL AND AIR IN A DESERT.
By JOHN G . SINCLAIR. .
[Mediml School, University of North Dakota, Msrrh 15,1922,)
The Carnegie Institution of Washington maintains a Desert Laboratory at Tucson, Ariz, where for sonie years the activities of plants and ammals in relation to their desert envir0nmen.t. have been studied. Much work has been done with water-relations both as to eva ora-
and air temperature are kept. While assist-ant in charge of Professor Tower’s “ Esperi- men& in Evolution” (see Carne ie Publication No. 263)
tions of air and soil. The results have a meteorological as well as a biological interest. It is a well-recognized fact that the range of temper- atures in the desert is tremendous. The surface of the soil is heated and it is a matter of interest t.0 know to what extent this heat is transferred to deeper levels. I t is well known that the surface air becomes rapidly chilled in the evening. What is the relation of temperaturo here to the levels above and the soil beneath ? Desert animals and plants live in a comparat.ively narrow zone. There were available at Tucson an exceptional aggre- gation of thermometers. The measurements in air were taken with German-made instruments, having large bulbs and graduated to tenths of a degree centigrade. These instruments were divided into two sets. One set was coated with a glossy white paint and the other with a dull black. I anticipated cnticisms of this and so t.ook the recaution to read t,he standard shelter t,hermometer
Since they were to be used in the open sunlight, the entire lot were standardized. To do this they were placed at a uniform level about 4 feet! above ground and readings were taken every hour of the day. The ther- mometers were inclined, so that their axes were a t right angles to the circle of the sun, insuring uniform exposure at all times. The members of each set differed only by tenths of a degree from each other. The constant neces- sary to reduce each to the median member of the group wm adopted for each thermometer and for each hour of the da separately. All further data were then cor-
The soil temperatures were read on standard mercury thermometers, which, like the others, had to be checked
tion and movement in soils. Extensive records o F soil
I undertook a further analysis o f? the temperature condi-
at t rl e same time that any other readings were taken.
rected g y these constants.
in a water bath for com arison.
as the temperature there burst the one h t employed. At two of tshe levels Friez soil thermographs registered continuously and the records from other instruments were available for comparison but from a different locality. e 1 illustrates in dia am the apparatus set u .
same and the exposure was made uniform through the day as in the tests. The u per sis soil thermometers ermanently embeddef and were read in place. The were x e th indicated the distance to the center of the bulb. !‘he thermometers for the deeper levels were slipped into close-fitting glass tubes, so that the bulbs rested in molds in the soil below. These were drawn up rapidly by strings sufficiently hi h to be read and were
It. was found necessar to use a boiling-point t R ermometer for the surface so$
The K“ evels of the black and w%te thermometers were t % e
Fi
immediately dropped back and t a e tube corked. After the preliminary tests the 5:30 a. m., June 17, 1915. and continued to 10:30 p. m. The series was repeated September 19, 1915. An inspection of a repetit.ion of the main features daily. For this reason that day was chosen for presentation which showed the highest temperature reached for the year. This was June 31, 1915. Table 1 shows bhe data taken June 21. In the table the data for air and soil temperatures are separated at the ound level. At this point are placed the readings
added interest readings taken in shade among the red volcanic rocks of the Desert Laboratory grounds. All the apparatus exce t this one thermometer recorded the
the rocks. The masimum temperatures reached in the air series at any time of day are in bold-faced type and are arranged to compare the black and white t;hermom- eters with the standard shade temperature. The minimum temperatures for any time of day are given in italics. The peculiar shift of the point of masimum and minimum tem eratures is a significant
righ and the earth is much hotter than the air immedi- ately above it.
of t l? e standard shelter thermometer and as a matter of
conditions in the a c f obe soil of the garden well away from
roblem. At-4:30, when this s t: ’ft occm, the sun is still