american society for testing and materialammonia fixationammonium enterapmentammonium fixationamorphousamorphous materialamphibiousamplification factoramplitudeanabatic windanabranchanaerobaticanafrontanalog simulatoranalysisanalytycal procedureanamorphic zoneanchor iceanchorageanchored tree portectionandeptsandisolsanemogramanemographanemometeraneroid barographaneroid barometerangle of reflectionangle of resposeangle of restangle of rreposeangle restangularangular topographyangular velocityangularityangulateangulationangule of contactanimal unitanion exchange capacityanion exclusionanion repulsionanisotropic aquiferanisotropyannual drainage patternannual floodannual peak floodannual variationantarctic