artificially enduced precipitation

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ARTIFICIALLY ENDUCED PRECIPITATION

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ARTIFICIALLY ENDUCED PRECIPITATION

Weather Modification/Weather Control -general term for

efforts to alter the natural meteorological phenomena of the

atmosphere.

Cloud modification/Cloud seeding - is the attempt to change

the amount or type of precipitation that falls from clouds, by

dispersing substances into the air that serve as cloud condensation

or ice nuclei, which alter the microphysical processes within the

cloud.

- the most common chemicals used for cloud seeding

include: silver iodide, potassium iodide and dry ice( solid carbon

dioxide).

INTENSITY OF RAINFALL

Intensity of Rainfall -is defined as the ratio of the total amount

of rain (rainfall depth) falling during a given period to the

duration of the period. It is expressed in depth units per unit time,

usually as mm per hour (mm/h).

•Rainfall intensities

1. Light-when the precipitation rate is < 2.5 mm (0.098 in) per

hour

2. Moderate-when the precipitation rate is between 2.5 mm

(0.098 in) - 7.6 mm (0.30 in) or 10 mm (0.39 in) per hour

3. Heavy-when the precipitation rate is > 7.6 mm (0.30 in) per

hour or between 10 mm (0.39 in) and 50 mm (2.0 in) per hour.

Rain Gauges -also known as an udometer,

pluviometer, or an ombrometer is a type of

instrument used to gather and measure the

amount of liquid precipitation over a set period of

time.

•Most commonly used recording rain gauge:

1. Standard rain gauge-consists of a funnel

emptying into a graduated cylinder, 2 cm in

diameter, which fits inside a larger container

which is 20 cm in diameter and 50 cm tall.

2. Tipping bucket rain gauge-consist of a

plastic collector balanced over a pivot.

When it tips, it actuates a switch which is

then electronically recorded or transmitted

to a remote collection station. The tipping

bucket rain gauge is not as accurate as the

standard rain gauge because the rainfall

may stop before the lever has tipped.

3. Natural siphon rain gauge(float type rain

gauge) -A class of rain gage in which the level of

the collected rainwater is measured by the

position of a float resting on the surface of the

water; frequently used as a recording rain gage

by connecting the float through a linkage to a

pen which records on a clock-driven chart.

4. Weight Bucket rain gauge