Weather Instruments, Maps and Charts

The atmospheric condition of elements like temperature, pressure, wind, humidity and cloudiness at a particular place and time is called weather. Weather observations are coordinated by the World Meteorological Organisation.

Weather based observations are recorded in Surface Observatories, Upper air Observatories and Space based Observation Platforms. The instruments used for measuring the weather phenomena are: Thermometer (Maximum and Minimum Thermometer, Dry and Wet Bulb Thermometer) Wind Vane Rain Gauge Barometer (mercury and aneroid) and, Stevenson screen The different weather phenomena are recorded and represented in different ways. A weather map is the representation of weather phenomena of the earth on a flat surface. These maps depict the conditions associated with different weather elements on a particular day. Weather charts provide the primary tool for weather forecasting. Weather charts are prepared from the data, regarding weather phenomena, received from the various observatories. The data is detailed and in plenty. Weather symbols are special codes designed with the help of the data received from various weather observatories. These symbols are standardised by World Meteorological Organisation and, National Weather Bureaus. Weather maps and charts are prepared regularly since the opening of the Indian Meteorological Department. The climatic data is mapped using isometric lines. These lines are depicted on the map as isopleths. Some different types of isopleths are: Isobars: Lines connecting places of equal air pressure Isotherms: Lines connecting places of equal temperature Isohyets: Lines connecting places of equal amount of rainfall over a given period of time Isohels: Lines connecting places of same mean daily duration of sunshine Isonephs: Lines connecting places of same mean value of cloud cover With the interpretation of the weather maps, we can analyse the general pattern of the weather conditions prevailing in the different parts of the country.

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