tween east and west in the southern Marshalls,

The easterly winds

extend to great heights, reaching in some instances from the surface to 60,000 feet.

Fluctuations in the easterlies are due to the

passage of atmospheric waves traveling from east to west at a speed
of approximately twelve knots,

Thus the eastern Marshalls are af-

fected by the wind shifts before the western Marshalls,

Some of

these waves become transformed into cyclonic circulations which
show up on wind maps as vortices or eddies, similar, though on a
larger scale, to the eddies seen on the surface of rivers,

In

contrast with the just described upper cyclonic situation in which
cyclones have their origin in the high atmosphere, the transforma-

tion from wave to vortex for this situation occurs first in the
lower atmosphere and gradually extends upward.

In general, bad

weather is associated with the west-southwest and southeast winds
accompanying the rear portions of the vortex,
of the waves from which the vortices originate,
is associated with the southeast winds,

This is also true
The worst weather

There is a tendency for

this weather to appear in the form of long lines of cumulo-nimbus

cloud bearing striking resemblance to the cold fronts of high
latitudes; but they are more numerous than the latter within an
‘equivalent area,

Many vortices are quite weak; that is to say,

maximum wind speeds—-usually found in the southeasterlies--do not
exceed thirty knots,

But there is always the likelihood of a4 vor-

tex intensifying suddenly to become a typhoon,

The best known ex-

amples were Typhoons GEORGIA and JOAN which intensified over the

169

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