San Francisco water . ishes the parched sur- face, causing vegetable growth, runs downrivers to the sea, is used by man in commerce,and is harnessed and caused to turn thewheels of industry. But the most importantuse of water is its consumption by man andbeast to sustain life, and in this last use weare particularly interested. Most rain-storms on the Pacific Coastcome off the North Pacific Ocean and travelin an easterly direction across the mountainregions to the valley of the storms have two motions: a forwardmotion and a rotary motion. They rotatearound their own center co
San Francisco water . ishes the parched sur- face, causing vegetable growth, runs downrivers to the sea, is used by man in commerce,and is harnessed and caused to turn thewheels of industry. But the most importantuse of water is its consumption by man andbeast to sustain life, and in this last use weare particularly interested. Most rain-storms on the Pacific Coastcome off the North Pacific Ocean and travelin an easterly direction across the mountainregions to the valley of the storms have two motions: a forwardmotion and a rotary motion. They rotatearound their own center counter-clockwise—that is, from right to left—and have a for-ward motion from west to east. The center ofa storm is an area of low atmospheric pres-sure. As water flows from a high to a lowpoint, so does air travel from a region ofhigh pressure to one of low pressure, caus-ing winds. When a storm is approaching usoff the Pacific Ocean from the northwest, thewind is blowing from the southeast, and SAN FRANCISCO WATER. Recording thermometer and barometer used by SpringVallev Water Co. at Sunol, Alameda County after the storm has passed to the southeastthe wind comes from the north. Thus by ob-serving the atmospheric pressure (by theaid of a barometer) and wind direction, oneis fairly able to forecast the approach ofstorms that have already formed out on thePacific Ocean. The United States Weather Bureau ex-plains this in a note printed on their DailyWeather Map, as follows: Wind-barometer Indications.—When thewind sets in from points between south andsoutheast and the barometer falls steadily,a storm is approaching from the west ornorthwest, and its center will pass near ornorth of the observer within 12 or 24 hourswith wind shifting to northwest by way ofsouthwest and west. When the wind sets infrom points east and northeast and the ba-rometer falls steadily, a storm is approachingfrom the south or southwest, and its centerwill pass near or to the south or east of theobserve
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectwatersupply, bookyear
