what are the steps taken to introduce the latest meteorological instruments
Answers
Measurement of solar radiation
The best alternative for the design, sizing, and performance evaluation of a solar facility is using registered data. In general, the most detailed information available is beam and diffuse solar radiation on a horizontal surface and, sometimes, the normal beam component can be also found.
The simplest of the devices devoted to solar records is the heliograph (Campbell-Stokes recorder). It consists of a glass sphere with a diameter of 10 cm designed to focus the sun's rays onto a black card mounted at the back. The sphere is set on a stand and the card is held in place by grooves of which there are three overlapping sets, to allow for the altitude of the Sun during different seasons of the year. The recording of each day goes onto one card. Each card is marked as to the hour, with local noon being in the center, and is read in tenths. The bands are different for each period of the year. The major advantage of this instrument is its simplicity and ease of use. There are no moving parts and it thus requires very little maintenance.
The meteorological instruments designed to measure solar radiation are generally called solar radiometers. They all include a sensor that converts the received radiant energy into an easily recordable electrical signal. Depending on the process of conversion of the received energy it is possible to distinguish the following categories:
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Bimetal sensors. They are based on the thermomechanical properties of a bimetallic tape that is stretched according to the incident solar energy.
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Calorimetric sensors. Solar energy is transformed into heat energy and induces a variation of the temperature of the sensor that allows evaluating the heat flow and the amount of incident energy that causes it.
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Thermoelectric sensors. They are based on the Seebeck effect (electrical potential difference proportional to the temperature difference between two solders) and respond to a broad spectral range of radiation. That response is stable against temperature variations.
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Photoelectric sensors. They are based on the photovoltaic effect (electric current on the junction of two semiconductors). They are cheap and have a quick temporary response but, as a drawback, they are very sensitive to temperature variations and their spectral response is limited.
Instruments for measuring solar radiation are of two basic types, pyrheliometers and pyranometers. A pyrheliometer is an instrument using a collimated detector for measuring beam solar radiation (from the Sun and from a small portion of the sky around it) at normal incidence. A pyranometer is an instrument for measuring total (beam plus diffuse) hemispherical solar radiation, usually on a horizontal surface. If shaded from the beam radiation by a shade ring or disc, it measures diffuse radiation.