|Kew Pattern Barometer
The Kew Pattern Barometer is the standard type of
barometer used to measure atmospheric pressure.
The barometer, the single most important meteorological
instrument, measures atmospheric pressure. The invention of the mercury barometer in 1643 by Evangelista
Torricelli depended on his realization that air has weight.He noted
that if the open end of a glass tube filled with mercury is inverted in a bowl of mercury, the atmospheric
pressure on the bowl of mercury will affect the height of the column of mercury in the glass tube. The greater
the air pressure, the longer isthe mercury
The Rainfall Gauge is used to measure the amount of
rainfall over a specified area.
gauge is composed of three parts: a funnel, a measuring tube, and a 4-inch diameter overflow tube. The funnel
directs the precipitation into the measuring tube and magnifies it by a factor of 10. This allows observers to
report rainfall to the nearest 0.01" (one hundredth of an inch). The measuring tube, when full, will hold "one
inch" of rainfall. When it rains more than one inch, the excess water collects in the overflow
The Thermometer is used to measure air
A thermometer measures temperature.
Liquid-in-glass thermometers are the most common types of thermometers because they are easy to read and
inexpensive to construct.
thermometers are made from glass and consist of a glass bulb that is attached to a tube that is marked with a
temperature scale. The liquid in the thermometer is usually alcohol or mercury. When this liquid warms up, the
molecules in the liquid move faster and the volume expands. The expansion of the liquid causes it to move up
into the bore and indicate the temperature. When the liquid cools, it contracts and moves back into the bulb,
indicating a low temperature.
thermometer with a constriction is used to measure the maximum temperature. These types are thermometers are
also used to measure the body temperature of humans. As the temperature increases, the liquid moves up into the
bore; however, as the liquid cools, it cannot freely move downward again because of a constriction in the bore.
In order to lower the liquid in the bore, it must be reset by applying forces to the thermometer sufficient to
push the liquid bask into the bulb.
The Hand Anemometer is a small
portable instrument that gives a direct reading of wind speed.
Wind is air in motion. Differences in air temperature
create differences in atmospheric pressure which, in turn, initiate air motion. This movement is modified by
the rotation of the earth, which causes the wind to deflect to the right in the Northern Hemisphere. Another
important factor is friction. High above the earth the flow of air is smooth and continuous. At or near the
ground this uniform flow is disturbed by the irregularities of the earth's surface. Generally, the effect of
these irregularities is to make the flow lighter but more variable, with lulls and
The Campbell-Stokes Pattern Sunshine Recorder is used to measure the
duration of sunshine, (that is, the number of hours of sunshine per day).
This is a tropical pattern
suitable for use in the latitudes 5 Degrees South to 45 Degrees North. Bowl made of Tin Bronze surface finished
black painted and hard Lacquer, with cut glass sphere mounted concentrically in a section of the spherical bowl,
the diameter of which is such that when the instrument is exposed to sun rays they are sharply focused on a card
held in the grooves of the bowl, the focused sunray's burn a trace on the recording card which has a time scale
printed on it. The length of the burn indicates the period of bright Sunshine during the day. Complete in a wooden
box with the recording cards for one year.
The purpose of the Stevenson Screen is to create
a uniform temperature enclosure that closely represent the same temperature as the air
The screen is designed to shield thermometers from
precipitation and direct radiation from the sun, while allowing air to circulate freely round them. It houses
maximum and minimum thermometers and a wet and dry bulb hygrometer. It is made from wood with louvered sides to
allow the free and even flow of air. The front panel is hinged at the bottom to form a door, which allows for
maintenance and the reading of the thermometers. The whole screen is painted white to reflect
Weather balloon &
Radiosonde is agroup of instruments
for simultaneous measurement and radio transmission of meteorological data, including temperature,
pressure, and humidity of the atmosphere.
The instrument package is
usually carried into the atmosphere by a balloon. Balloon-borne radiosondes can reach altitudes as great as
90,000 ft (27,400 m) above the earth's surface. A radiosonde may also be carried by a rocket, in which case
it is known as arocketsonde, or dropped by parachute (usually from an aircraft), in which case it is known as
Instruments included in a radiosonde are typically transducers for humidity, temperature, and pressure
measurements; controls to improve return signals and determine which measurements are to be transmitted to
data stations; and a radio transmitter. Radar also has been used to measure and transmit meteorological data
from a radiosonde. These radiosonde observations are made as often as two times daily at some meteorological
stations around the globe.
The Ceilometers is an instrument that measures
cloud-bottom heights and vertical visibilities.
The Ceilometer is a self-contained,
ground-based, active, remote-sensing device designed to measure cloud-base height at up to three levels and
potential backscatter signals by aerosols. Model CT25K has a maximum vertical range of 25,000. The ceilometer
transmits near-infrared pulses of light, and the receiver telescope detects the light scattered back by clouds
Total Sky Imager
The Total Sky Imager is an instrument that
measures Fractional sky cover and Sun obscuration by cloud.
The Total Sky Imager provides time series of hemispheric
sky images during daylight hours, and retrievals of fractional sky cover for periods when the solar elevation
is greater than 5 to 10 degrees.
The Total Sky Imager is an automatic, full-color sky imager system
that provides real-time processing and display of daytime sky conditions. An onboard processor computes both
fractional sky cover and sunshine duration, storing the results and presenting data to users via an easy-to-use
web browser interface. It captures images into standard JPEG files that are analyzed to infer fractional sky