| Show New Ideas Expected to Aid Weather Prophets Air mass masa analysis methods for tor which have have been developed largely daring the last decade Is II rapidly assuming as- as lumina laming an Important place lare In forecasting forecasting forecasting fore fore- casting the weather Greater detail In n observational material than Is I. ordinarily or or- available Is n necessary for tor such inch forecasting The mass air mass analysts analysis method of forecasting calls for the study of two or more con conflicting masses mustS of ot air usually of widely widell different origin and consequently of different characteristics char char- 1 as II to temperature and moisture which come together along what Is II called caned a line of discontinuity ity a polar front or a wind shift Air over polar ret of course Is much colder than that over o trop teal ical regions The transition however Is II neither gradual nor regular Instead Instead In In- stead large masses of air In one or orthe orthe orthe the other region become or superheated These Theo masses musts develop devel devel- op into surges or bulges that meet along an Irregular line tine Because Because Be ne- cause they tiler differ structurally In teme temperature tem lem- and moisture and therefore density the masses muses do not mix In an orderly fashion but tend to preserve their own Identities This Thle results In a battle for supremacy which forms the ever changing drama that Is our weather The air from the polar regions Is II cold dry heavy and relatively cloud cloud- less leis That from the tile tropical regions Is warm moist relatively light bt and cloudy cloud At the line where they meet the advancing tropical air being warm moist molet and therefore lighter Is II forced force to ascend and flow northward northward northward north north- ward over the wedge of ot cold air at atthe atthe atthe the surface This called Is-calleJ the warm front The air as It rises Is II cooled by expansion and the moisture In ItIs It ItIs itIs Is condensed Into clouds from which rain or snow may fall The amount and duration of this precipitation depend on several factors Including wind direction amount of moisture slope of ot air wedges dge and rapidity of warm arm air ascent Along the cold front the lag ng polar or cold air forms a wedge or thrust under the warm air and the he precipitation Is squally equally usually however covering only a compare small small area arcs Accompanying these thelle precipitations precipitation are ara marked and sudden chan changes s In to temperature and wind followed by a amore amore more or less lens steady Heady state until the next meeting of conflicting on air masses mals when the drama Is la re re-en- acted |
