_Beaufort Scale._--A scale of wind force, originally devised for use at sea, but now used also on land. The scale runs from 0 = calm to = hurricane. Many other scales are similarly employed in the noninstrumental observation of wind force. _Bioclimatic Law._--A phenological law, announced by Dr. A. D. Hopkins, according to which periodical events of plant and animal life advance over the United States at the rate of 1 degree of latitude, 5 degrees of longitude, and 400 feet of altitude every four days--northward, eastward, and up-ward in spring, and southward, westward, and downward in autumn. _Bishop’s Ring._--A large corona due to fine dust in the atmosphere. It has been seen after certain great volcanic eruptions, especially that of Krakatoa, in 1883. _Blizzard._--A violent, intensely cold wind, laden with snow. _Blowing Well._--A well which emits a strong current of air from any small opening in its cover during a fall of barometric pressure. During a rise of barometric pressure such wells are sometimes observed to “suck.” Wells that are thus responsive to barometric changes are sometimes called “barometer wells” or “weather wells.” _Bora._--A cold wind of the northern Adriatic, blowing down from the high plateaus to the northward. Also, a similar wind on the northeastern coast of the Black Sea. _Brave West Winds._--The boisterous westerly winds blowing over the ocean between latitudes 40 and 50 degrees S. This region is known as the “roaring forties.” _Bright Segment._--The broad band of golden light that, in clear weather, borders the western horizon just after sunset and the eastern just before sunrise. _Brontide._--A sound resembling a distant muffled detonation, usually indefinite as to direction. Brontides are rather common in certain parts of the world. They are called _mistpoeffers_ on the Belgian coast, _Barisal guns_ in the Ganges delta, _bulldag_, _desert sounds_, or _Hanley’s guns_ in parts of Australia, _gouffre_ in Haiti, _Moodus noises_ at Moodus, Connecticut, _Nebelzerteiler_, _Seedonner_, _Seeschiessen_, etc., in Germany, _baturlio_, _boniti_, _bombiti_, etc., in Italy. These sounds are probably of subterranean origin in most cases. _Bump._--An upward jolt experienced by an aviator, as if running over an obstruction. A bump may be caused by any condition that suddenly increases the lift of the machine, but is perhaps most frequently due to rising air currents. Air in which bumps are experienced is said to be “bumpy.” (Cf. _hole in the air_.) _Callina._--A Spanish name for dry fog. _Calms of Cancer_; _Calms of Capricorn_.--The belts of high pressure lying north of the northeast trade winds and south of the southeast trade winds, respectively.