File:Smithsonian miscellaneous collections (1921) (14598485988).jpg

Identifier: smithsonianmisce691921smit (find matches)
Title: Smithsonian miscellaneous collections
Year: 1862 (1860s)
Authors: Smithsonian Institution
Subjects: Science
Publisher: Washington : Smithsonian Institution
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Smithsonian Libraries

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lling M the tangent made by the best repre-sentative right line with the X axis, then Ntp may be obtained throughthe equation N _ 32-3. pXIO3 I tP 3 0.8l (I + at)760 M Figure 1 shows the graphical steps and the following table the result-ing values: Table 5.—Number of Molecules Nt(), derived from the Transparency ofAtmospheric Aqueous Vapor Year M x io12 v^(i+a0 76oXIo_17 < liade D I9IO 0.88 4-7 Good. 0.015 I9II .98 4.2 Good. .015 1913 1.52 2.7 Excellent. .025 1914 .70 5-9 Poor. .014 1915 • 52 7.9 Excellent. .018 I9l6 • 49 8.4 Excellent. .013 1 For shorter wave-lengths greatly decreased transmission is found as thegreat metallic reflection band at 0.115 m is approached (Martens, Annalender Physik, 6, p. 603, 1001), and for wave-lengths greater than 0.50 m as a regionof selective absorption is approached. For metallic reflection and selectiveabsorption the molecular formula would not hold. 3 Astrophysical Journal, 38, p. 400, 1913. SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 69
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$ <-CO o o o o «-m oo — -tD o d O < o CD o ino o CO O O no. 3 ATMOSPHERIC SCATTERING OF LIGHT FOWLE Over the region plotted k may be considered equal to i — a„x, thatis the scale of ordinates of figure i represents approximately thefractional absorption of energy by i cm. of precipitable water in theform of atmospheric vapor. The data for wave-lengths to the rightof the region shown (wave-length less than 0.35 /*) and to the left(greater than 0.60 fx) are very inaccurate, the first because of spectro-scopic field-light and very small measurable quantities, and thesecond because of selective absorption. The accuracy with which theobservations fall on a straight line is beyond expectation. Withinthe wave-length limits just named the average departures from astraight line for the different years correspond in absorption asfollows: Year 1913 1915 1916 0.2 0.2 0. I (1913, omitting poor points.) The mean value of Ntp obtained from the atmospheric aqueouswater vapor is about P w

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