| Element ||Definition|
Hydrometeor consisting of a fall of ensemble of particles. The forms of precipitation are: rain, drizzle, hail, ice pellets, snow, snow pellets, and grains.
|Daily Maximum temperature||Maximum temperature during continuous time interval of 24 hours.|
|Daily Minimum temperature||Minimum temperature during continuous time interval of 24 hours|
|Dry bulb temperature||Temperature indicated by a bare bulb thermometer exposed to the air and sheltered from direct solar radiation.|
|Wet bulb temperature||Temperature read from a wet-bulb thermometer exposed to the air but sheltered from direct solar radiation.|
|Dew point temperature||The temperature to which volume of air must be cooled at a constant pressure and constant moisture in order to reach saturation; any further cooling causes condensation.|
|Soil temperature||Temperature observed at different depths in the soil.|
|Humidity||Water vapour content of the air.|
|Relative humidity (RH)||A type of humidity that considers the ratio of the actual vapor pressure of the air to the saturation vapor pressure. It is usually expressed in percentage.|
RH1-calculated from dry and wet bulb temperature.
RH2-Relative humidity takenfrom thermo-hygrograph chart reading.
|Wind||Air that flows in relation to the earths surface, generally horizontally.|
|Wind speed (at 2mts above the ground)||The rate of the motion of the air on a unit of time.|
|Wind direction (at 10mts above the ground)||The direction from which the wind blows.|
The sum of all time periods during the day when the direct solar irradiance equals or exceeds 120 W/m2. This measurement is only obtained from configurations that measure direct solar irradiance.
| Evaporation||Emission of water vapour by the free surface of liquid water at a temperature below its boiling point.|
|Weather|| - The state of the atmosphere at a particular time as defined by various meteorological elements.|
- Present weather: - weather existing at a station at the time of observation.
- Past weather: -Predominant characteristic of the weather which had existed at an observing station during a given period of time.
|Pressure||The force per unit area exerted by the weight of the atmosphere above a point on or above the earths surface.|
Pressure deduced from the reading of a barometer at the station after applying instrument corrections and, if necessary, reducing its value to the height of the station
|Mean sea-level pressure||Atmospheric pressure at mean sea level calculated from the observed pressure.|
|Pressure tendency||Character and amount of a station pressure change over three hours (over 24 hours in tropical regions).|
|Horizontal Visibility||Maximum distance at which an observer may see and identify an object lying close to the horizontal plane on which he is standing.|
|Cloud||A hydrometeor consisting of minute particles of liquid water or ice, or of both, suspended in the free air and usually not touching the ground. It may also include larger particles of liquid water or ice and non-aqueous liquid or solid particles such as those present in fumes, smoke and dust.|
|Low cloud||Cloud of low cloud etage. Stratus and stratocumulus are almost invariably low-level clouds. The base of the low cloud is from earths surface upto 2km.|
|Medium cloud||Cloud of medium cloud etage. Altocumulus is almost invariably a medium-level cloud. The base of the medium cloud is 2 upto 8 km.|
|High cloud||Cloud of high cloud etage. Cirrus, cirrocumulus and cirrostratus are high-level clouds. The base of the high cloud is 6-18km.|
|Total cloud amount||The fraction of the sky covered by the cloud of a certain genus, species, variety, layer, or combination of clouds.|