ese või eseme (alumine) osa, mille peal miski on, millele miski toetub, kinnitub

alumise pilve alapiiri püstvahemaa maa- või veepinnast, the height of the base of the lowest observed or forecast cloud element in the vicinity of an aerodrome or operating site or within a specified area of operations, normally measured above aerodrome elevation or, in the case of offshore operations, above mean sea level