artificially enduced precipitation
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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 -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