APPENDIX  I A ACCRETION —Growth or increase in size by gradual addition. ADVECTION—Horizontal transport of an atmospheric property solely by the motion of the atmosphere. AEROSOLS—Small droplets of liquid suspended in a gas, such as water in the air. AFWA—Air Force weather agency. AGL—Above ground level. Measurements suffixed by the  abbreviation  AGL  refer  to  height. ALIDADE —A  device  frequently  used  by  shipboard navigation personnel to sight objects and read either relative  azimuth  bearing  or  true  azimuth  bearing. AMBIENT—A representative reading or measurement  for  a  substance  under  surrounding conditions. ANALOG—Proportional  and  continuous.  An  analog recorder draws continuous lines proportional to the electronic signal input.    In  an  analog  signal,  the sound   pitch   varies   proportionately   with   the intensity of the signal, and the signal is continuous. ANEMOMETER —A device used to measure wind speed and/or wind direction. From the Greek word anemo, meaning wind, and modem word meter, meaning measurement device. ANEROID—Without  fluid  or  without  water.  An aneroid barometer uses no fluid (mercury). ANOMALOUS—Irregular  or  abnormal. ANTICYCLONIC—Any   rotational   motion   in   a clockwise  manner  in  the  Northern  Hemisphere,  or  a counter—clockwise  manner  in  the  Southern Hemisphere. APPARENT—The  way  something  appears  or  is perceived,  although  it  may  not  be  true. ARQ—Automatic response to query. A method of obtaining data by using AFMEDS or CMW. ASCENSION—Rising  or  increasing  in  elevation. ASOS—Automated  surface  observing  system. AWSP—Air weather service pamphlet, now AFP or Air  Force  pamphlet. AZIMUTH—The horizontal angular measurement from a fixed reference to a point. The Navy uses angular  measurements  in  clockwise  degrees  from  0 to 360. When 0 is referenced to true north, the result is a true azimuth bearing. When referenced to an arbitrary direction, such as the bow of a ship, the result is a relative azimuth bearing. B BACKING—A   change   in   wind   direction   in   a counterclockwise   manner   in   the   Northern Hemisphere,  or  a  clockwise  direction  in  the Southern Hemisphere. BATHYMETRY—The features and depths underwater. BATHYTHERMOGRAPH—Any   device   used   to measure  and  record  temperatures  through  a  column of water. C CALVE—The process of splitting ice from a glacier to form icebergs. CCTV—Closed circuit television. CEILOMETER—A more sophisticated and automated  clinometer  used  to  measure  cloud  or ceiling heights. CIC—Combat information center aboard ship. CLIMATIC—Any   element   associated   with   the climate of an area. CLIMATOLOGY —The   study   of   the   statistical means,  frequencies,  deviations,  and  trends  of weather elements for an area over a period of time. CLINOMETER—A device used to obtain an angular elevation measurement of a light spot on a cloud base to determine the cloud or ceiling height. The distance between the meter and the light source must be known. AI-1 GLOSSARY