CONTENTS 



CHAPTER PAGE 



Summary . . . I 



I. Program and history of the expeditions 3 



II. Historical survey 12 



III. (a) Theory of the radiation of the atmosphere 18 



(b) Distribution of water vapor and temperature in the atmosphere 24 



IV. (a) Instruments 28 



(b) Errors 31 



V. Observations of nocturnal radiation 33 



It, Observations at Bassour 33 



2. Results of the California expedition 37 



(a) Influence of temperature upon atmospheric radiation. . 37 



(b) Observations on the summits of Mount San Antonio, 

 Mount San Gorgonio, and Mount Whitney, and at Lone 

 Pine Canyon. Application in regard to the radiation of 

 a perfectly dry atmosphere and to the radiation of the 

 upper strata 42 



(c) Observations at Indio and at Lone Pine 50 



(d) The effective radiation to the sky as a function of time. 52 



( e) Influence of clouds 54 



VI. Radiation to different parts of the sky 57 



VII. Radiation between the sky and the earth in the daytime 70 



VIII. Applications to some meteorological problems 76 



(a) Nocturnal radiation at various altitudes 76 



(b) Influence of haze and atmospheric dust upon the nocturnal 



radiation 80 



(c) Radiation from large water surfaces 83 



Concluding remarks 87 



APPENDIX 



I. Free-air data in Southern California, July and August, 1913. By 

 the Aerial Section, U. S. Weather Bureau. Wm. R. 



Blair in charge 107 



II. Summary of spectrobolometric work on Mount Wilson during Mr. 



Angstrom's investigations. By C* G. Abbot 148 



III. Some pyrheliometric observations on Mount Whitney. By A. K. 



Angstrom and E. H. Kennard 150 



