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30.000 Trade Situation
The first weather situation may be called the "‘trade’” situation..
Over the
Marshall Islands, . north of 5° N, eastenaxth-east ‘to northeast winds prevail in the
lower levels of the atmosphere; ‘the wind speeds -range -between 5 -ond 10 knots from
the equator ‘to 10° N, increasing ‘to as much -as 20 knots in the region -between
Eniwetok and Wake..
Small -omounts -of cumulus ‘clouds ‘(usually cbhout 5/10 coverage}
are found in this -current -and the clouds -do ‘not -extend much -chove 8.000 ‘feet ‘in
the north nor above 12.000 feet in the southern Marshalls.
Rain sometimes ‘falls
from some of these clouds, parficularly -in the south, but it is usuallyin the -form
of light showers.
No extensive middle o: upper cloud decks -are found.
Although
the lower winds -are northeasterly ‘ond quite ‘fresh, as one -ascends in the atmosphere over the northern Marshalls, one -finds ‘that -the -winds ‘turn moze ‘westerly -with
elevation, until-at-about 20,000 -feet they -lie between ‘northwest and southwest.
The
westerlies then extend -upwards:to ‘the tropopause, increasing in speed -to -obout 35
knots at 45,000 feet.
If the -uppe: ‘winds -in -the -region -should -be mainly south-
‘westerly, rain-from-the-trade-cumulus -is likely -ond the -amount of -cloud may iacrease
‘from time to time to as much -cs 8/10..
On -the other -hand, -if -the -upper -winds -are
chiefly northwesterly in direction,, cumulus cloud may decrease-to .as ‘little .as 2 of
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The variation between northwest ond southwest is
§
3/10 and showers are less likely.