Atmospheric

(at-mos-fe?-’ ’ -ik) [dr//oc, vapor; apalpa, a sphere]. Pertaining to the atmosphere. A. Moisture, the vapor of water mingled with the atmosphere. It varies in quantity according to the temperature. A. Tension, the pre ure of the air per square inch on the surface of a body. Normally, at the sea level, it is about 15 lbs. per square inch, or equal to that of a column of mercury about 30 in. in height. It decreases about TL in. or J5 lb. per square inch for every 90 feet of altitude. Above 10,000 feet, the rarity of the atmosphere is usually noticeable in quickened breathing and pulse-rate. 98