Use of Weather Charts

Weather charts are representations of weather phenomena of the world or a portion of it on a flat surface. A given day represents circumstances linked with various meteorological factors such as temperature, rainfall, sunlight and cloudiness, wind direction and velocity, and so on. Such observations, made at certain times, are coded and forwarded to forecasting stations. The central office maintains a record of the observations, which serves as the foundation for creating a weather map. Upper air observations obtained from hill stations, aeroplanes, pilot balloons, and other sources are displayed individually.

Weather maps and charts have been produced regularly since the beginning of the Indian Meteorological Department. Meteorological observatories provide data twice a day to the Central Observatory in Pune. Data is also gathered about ships sailing in the Indian Ocean. With the creation of weather observatories in Antarctica, the International Indian Ocean Expedition, and the launch of rockets and weather satellites, significant progress has been achieved in the field of weather forecasting and observation.

Weather Charts

Data from many weather observatories are plentiful and comprehensive. As a result, they cannot be combined in a single chart. These are known as synoptic weather charts, and the codes they utilise are known as meteorological symbols. The major instruments for weather forecasting are weather charts. They aid in locating and identifying various air masses, pressure systems, fronts, and precipitation zones.

Line symbols are used to depict much of the weather data. The isometric lines are the most frequent of them. These lines are displayed as isopleths on the map. The Isopleth can be interpolated for locations with similar mean temperatures, rainfall, pressure, sunlight, clouds, and so on. Some of these lines and their applications are listed below:

Isobars: An isobar is a line of equal or continuous pressure on a graph, plot, or map; it is also known as an isopleth or pressure contour line. Isobars are lines drawn on a map connecting locations with equal average atmospheric pressure lowered to sea level over a set time. The barometric pressures displayed in meteorology are lowered to sea level, not the surface pressures at the map locations. Isobar distribution is strongly connected to the amplitude and direction of the wind field and can be used to forecast future weather patterns. Isobars are frequently used in weather forecasting on television.

Isotherms: An isotherm is a line that connects temperature-matched locations on a map. As a result, at the time stated, all sites through which an isotherm travels have the same or equivalent temperatures. The freezing level is defined as an isotherm at 0 °C. The phrase was invented by the Prussian geographer and naturalist Alexander von Humboldt, who produced the first map of isotherms in Paris in 1817 as part of his research into the geographical distribution of plants.

Isohyets: An isohyet, also known as an isohyetal line, is a line that connects sites with equal rainfall on a map during a specific period

Isohels: Lines connecting places of the same mean daily duration of sunshine

Isonephs: Lines connecting places of the same mean value of cloud cover

Interpretation of Weather Charts

We may use a weather map to comprehend the overall pattern of weather conditions in various sections of the country. The following are the general weather conditions in India during the month of May.

The pressure gradient is shifting to the north and north-east. There are two low-pressure areas, one over Rajasthan and the other over the Bay of Bengal. The low-pressure centre is highly formed over the Bay of Bengal, with concentric isobars and the lowest air pressure of 996 Mb. The sky in southern India is cloudy. In contrast, the centre section of India gets a typically clear sky. Winds sweep anticlockwise from the land to the sea at the southern part of the eastern coast.

Weather Map Symbols 

A high-pressure system is a region with elevated pressure in relation to its surroundings. It is denoted by an ‘H’ on the chart, with a number denoting the pressure. The wind travels counterclockwise around and away from a high-pressure system in the southern hemisphere. The air atop a high-pressure system lowers down and heats as it does so. Because sinking air is extremely stable, high-pressure systems indicate dry, steady weather with minimal winds.

A low-pressure system is an area of lower than normal atmospheric pressure. The wind blows counterclockwise around a low-pressure system in the southern hemisphere, and the air descends as it moves towards the centre of the low-pressure system. Because the air needs to go somewhere, it rises. As it rises, it cools and forms clouds. The symbol L is used for denoting low-pressure areas.

A cold front is the transition zone between warm and somewhat colder weather. It shows as a blue line with little blue triangles on the weather map (originally chosen because they look like little icicles). When cold, dense air passes through, it wedges beneath the warmer air ahead of it.

Warm fronts are depicted on the weather map as a red line with semi-circles. Warm fronts gradually replace cooler air with warmer air. A warm front’s temperature shift can be fairly considerable, much like a cold front’s, however, it tends to proceed more gradually than a cold front’s.

Conclusion 

The weather map, also known as a synoptic chart, is a simplified depiction of the Earth’s surface weather patterns that shows the positions and motions of the various systems. Weather charts are very useful in learning about a region’s weather conditions. They also can help in knowing about the climate of an area. In this article, we learned about the ways to interpret weather charts and what different symbols mean in a weather chart. Weather charts include various lines like isobars, isohyets among others.