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BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY Entered as second class matter at the Post Office, Worcester, Massachusetts, under Act of Aug. 24, 1912. Issued monthly except July and August. Annual subscription, $2.00; single copies, 20c. Address all communications to Charles F. Brooks, Secretary Blue Hill Observatory, Harvard University Milton, Mass., U. S. A. Vol. 16 MARCH, 1935 No. 3 AN OPPORTUNITY FOR AMATEUR METEOROLOGISTS Rare and beautiful optical phe- what is desired. If there is more nomena of the atmosphere are some- than one ring, the diameters of all times missed at the major observa- the rings should be measured with tories, being of somewhat local special care. The nature of the cloud occurrence. Meteorologists not con- or fog producing the corona, and the nected with such institutions have in state of the weather should be noted consequence an opportunity of con- in full. Circular halos round the sun tributing to knowledge by describing or moon should also be measured as and measuring unusual halos, coronas, accurately as possible, since it seems rainbows, as well as twilight phe- likely that halos of unusual radii are nomena and the colors of the sky. sometimes missed because the ob- This note is written with the idea server has made the not unnatural that the American Meteorological So- assumption that it is the ordinary ciety1 might thus be able to assemble 22° or 46° halo which he sees. The a large amount of accurate informa- inner diameter of such halos should tion regarding such phenomena; not be given, and also the width of the mere descriptions, but angular meas- band and a description of the colors. urements, especially of halos, rain- For the observation of halos and bows, and coronas. Assuming that coronas round the sun, a pair of dark the amateur will not be provided spectacles is almost a necessity. with a sextant or a theodolite, he The measurement of the radius of may still make measurements of a rainbow is not a simple matter, adequate precision by means of a because one cannot usually determine ruler held at arm's length, or by the center of the bow; but if there means of a carpenter's steel square are supernumerary bows (inside the held with the end of one side at primary bow or outside the second- the eye. ary) careful measurements should be made of the distribution of colors Measurements of coronas are of along any radius; in this way the special interest, because they make size of the drops may be arrived at. it possible to calculate the size of Iridescent clouds are special forms the water droplets which produce of the corona; their angular distance them. The angular diameter to the from the sun or moon is of great outer edge of the reddish ring is interest. Twilight phenomena and lrThe Pittsburgh session recommended that sky colors, and also mirages and phe- this suggestion be offered to the members through the BULLETIN.—Ed. nomena of extreme refraction, should Unauthenticated | Downloaded 10/05/21 06:35 PM UTC be carefully described, with whatever will only watch for them. Reports drawings and angular measurements from the United States should be sent the observer's ingenuity may suggest. to the Chief of the Weather Bureau It is felt that this is a field especi- at Washington; and from Canada to ally suited to the amateur meteor- the Director of the Meteorological ologist. He may be assured that he Service of Canada at Toronoto.— W. will see a surprising number of in- E. K. Middleton, Meterological Office, teresting optical phenomena, if he Toronto, Canada. ABSTRACTS AND DISCUSSIONS: PITTSBURGH MEETING (Continued from Feb. BULLETIN, pp, 33-42.) Observations of Condensation-Nuclei in the Atmosphere By DR. H. LANDSBERG, P'enn. State College. Seven hundred and forty-four ob- ocity. Stronger winds tend to dis- servations of condensation-nuclei in tribute the nuclei more equally in the atmosphere were made at a crest the vertical. The wind direction, too, and at a slope station of a German shows distinct influence on the num- mountain and these are discussed and ber of nuclei. Although local effects compared with 307 observations, a may influence this—winds travelling few of which were made on the North over larger parts of towns naturally Atlantic Ocean and the rest at State carry more impurities—the differ- College, Pennsylvania. ent meteorological air masses seem to The number of nuclei found on the be originally of different nuclear con- ocean, which is one of the sources tents. Thus polar air masses, which of atmospheric nuclei (in this case also show the lowest turbidity, carry salt crystals) is very small, usually the smallest amount of nuclei, while not exceeding about 1500/ ccm. The modified polar air and particularly most important sources of nuclei in tropical or old tropical air show two settled countries, however, are all to three times more nuclei. The processes of combustion. The ob- highest impurity, however, is found servations show that the impurities in the indifferent air masses which in the air, represented by nuclei, have stagnated a long time over a double when the heating period in certain locality. So the observations the fall starts. of nuclei help us, on the one hand, The history of nuclei in the atmos- to analyse air masses by testing the phere reveals interesting details. Ver- changes of nuclei at the fronts which tical currents transport the nuclei up- separate the air masses; on the other ward and downward. The first case hand, it seems that we may account (convection) makes the number near for some influences of the weather the surface decrease, thus improving on human health by the changing the visibility, while in higher levels conditions in the suspended impuri- the number increases. Downward ties in the air. This seems the more directed air currents seem to be of probable as it has been proved that large importance. During weather the nuclei are the carriers of the conditions of that type the number radioactive emanation in the air and of nuclei increases very much at a percentage as high as 40% of the the surface. The vertical distribution nuclei are absorbed by the human is also dependent on the wind vel- body in inhaling the air. These last Unauthenticated | Downloaded 10/05/21 06:35 PM UTC.