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 WEST INDIAN HURRICANES, AND OTHER NORTH ATLANTIC STORMS. From

Explanation atlantic route.

track, that

is,

the Pilot Chart of the North Atlantic Ocean, August, 1889, with Additional Paragraphs.

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These diagrams are for practical use in West Indian hurricanes. The upper one will also answer for ordinary storms alono- the transThe small arrows fly with the wind, the direction being stated at the end of each dotted line; the long arrow on each diagram is the storm the probable path of the cyclone through the belt of latitude to which the diagram applies.

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June and October, tsE lat. 23" to 55° July and Sept., lat.

29° to 55°.

August, lat. 33°

to 55°.

Stoem track, N NE. to E NE. Motion of storm center along track, miles per

June and October, lat.

E

20° to 23°.

July and lat.

Sept.,

27° to 29°

AUGUST, lat.

80° to 33.

Storm track,



NNW. to NNE. Motion of storm center, along track, 5 to 10 miles per hour.

June and October,

~iu

,,,/

lat. 10°

>>^S E

% NNW

V.





T

to 20°.

July and Sept.,

'

j*^

lat.

u/^vV

10° to 27°

ACGUST> lat. 10°

'"-ra^

to 30°.

Storm track, .A~ '

"*vs.v

SSE

r

W. by N. to N NW.

Motion of storm center along track, about 17 miles per hour.

Use of the Diagrams When a falling barometer, freshening rain squalls, &c, indicate a hurricane, select the proper diagram (according to the month and latitude), plot your position upon it by means of the direction of the wind, and thus ascertain the approximate bearing of the storm center. The probable storm track is indicated by the long arrow. If the wind shift, plot your position by means of the new wind-direction (nearer the center if the wind has freshened and the barometer has fallen). In this way you can readily observe every change of position relative to the storm center, and decide what action to take, according to the character of your vessel, the lay of the land. &c. These storms vary greatly in size, but are smallest and most violent in the tropics, where the cloud ring averages about 500 miles in diameter and the region of stormy winds 300 miles, or even less. You can therefore only roughly estimate the distance of the center, although its bearing can be obtained from the diagrams with a high degree of probability. There is also considerable variation in the direction of motion and the velocity of the storm along its track, but the general tendency is as stated herewith. Cyclonic Circulation One of the most important indications that an approaching storm is of hurricane violence is the marked cyclonic circulation of the wind, lower and upper clouds, etc. This may be easily appreciated by remembering that a cyclone of any great intensity is an ascending spiral whirl, with a rotary motion (in the Northern Hemisphere) against the hands of a watch, as shown on the diagrams The surface wind, therefore, blows spirally inward (not circularly, except very near the center); the next upper current (carrying the low scud and rain clouds), in almost an exact circle about the center; the next higher current(the high cumulus), in an outward spiral and soon, up to the highest cirrus clouds, which radiate directly outward. The angle of divergence between the successive currents is almost exactly two points of tho comOrdinarily, with a surface wind from N., for instance, the low clouds come from N., also; pass. on the edge of a hurricane, however, they come from N NE., invariably. In rear of a hurricane, the wind blows more nearly inward; with a SE. wind, for instance, the center will bear about W., the low clouds coming from S SE. (two points to the right of the wind), etc. Great activity of movement of the upper clouds, while the storm is still distant, indicates that the hurricane is of great violence. If the cirrus plumes that radiate from the distant storm are faint and opalescent in tint, fading gradually behind a slowly thickening haze or veil, the approaching storm is an old one. of large area; if of snowy whiteness, projected against a clear blue sky, it is a young

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cyclone of small area but great intensity. Intensified Trade-wind Belt. Another very important fact (established by Meldrum, at Mauritius) may be stated thus: When a hurricane is moving along the equatorial limits of a trade- wind region, there is a belt of intensified trades to windward of its track: not until the barometer has fallen about six-tenths of an inch it is safe to assume that, because the tradewind increases in force and remains steady in direction, you are on the track of the storm. By attempting too early to cross its track, running free as soon as the wind begins to freshen, you are liable to plunge directly into the vortex of the hurricane. General Information Hurricanes are especially liable to be encountered from July to Octothe Gulf of Mexico, and Gulf Stream ber inclusive in the tropics (north of the 10th parallel), very clear, pleasant Earliest indications: Barometer above the normal, with cool, region distant storm; light, feathery cirrua of the direction swell from the ocean weather- a Ion"-, low, whitish arc indicates the bearing of the clouds r'ldiatin"- from a point on the horizon where a halos about the sun and moon; increasing center' Unmistakable signs: Falling barometer; and violet tints at dawn ocpan 'swell' hot moist weather, with light variable winds: deep red the distant horizon; barometer falling more on bank mountainous cloud heavy,

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and sunset; 'a

3 wind, you are on the Brief Rules *)* Action.— If "the squalls freshen without any shift of on the starboard quarter and keep your compass course m t an i-. run off with the wind • Intensified Trade-wind Belt"). If the wind shift to the right entitled ? 2 caution w?nnir 111Paragraph is (see t(>rm t k t the snip on the starboard tack and make as much in tiic i »,,"< — 81 you ou are of the f !i°* hie until Obliged to lie-to. If the wind shift to the left, you are to the left possible, as *£J3 headway on the starboard quarter and keep your compass course; itf obliged wind the 1 t™*. hrins t in storm tiackh w&ys keep the wind weU on the ?taxboard quarter, gcuddi Always lie-to on the coming-up tack. L se oil to prevent heavy «"• of — the storm. iu" out iu run order to, in uruei ill board. seas from breaking on

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[Edition of July, 1S90.]

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