Thermodynamics and Engineering: Although these fields of study rarely involves a map contour lines finds usage in graphical representation of data and phase diagrams some of the common types of contour lines used in these fields of study are: Isoallobars in turn can be divided into the ketoallobars and the anallobars which represents the decrease and increase in the pressure change respectively.Ħ. Isoallobars joins points in the map with equal pressure change over a specific period of time. An isobar is a contour line that joins the regions with constant atmospheric pressure. The barometric pressure is reduced to sea level when represented in a map. Isopectic contour line denotes regions with identical or similar dates of ice formation while isotac refers to the thawing dates.īarometric pressure: In meteorology, the study of atmospheric pressure is important to predict future weather patterns.Isodrostherm refers to constant or equal dew point areas.Isohume refers to the contour line joining areas with constant relative humidity.Isobront joins points in map representing areas which experienced thunderstorm activity simultaneously.Isochalaz joins points in a map representing the areas receiving constant frequency of hailstorms.Isohyet or isohyetal line refers to equal rainfall regions in a map.Rainfall and humidity: Various terms are used to refer to the contour lines that join areas with similar precipitation and humidity content. An isogon refers to a constant wind direction.
Study of wind: In meteorology, a contour line joining points with constant wind speed is called as isotach. A contour line connecting areas with equal mean annual temperature is called as isogeotherms and that connecting areas with equal mean winter temperature is called as isocheim while that connecting equal mean summer temperature is called as isothere. Temperature study: These are a type of contour lines that connects points in a map with equal temperatures is called as an isotherm and those connecting areas with equal solar radiation is called as isohel. Since then there has been a widespread use of contour lines for mapping and other applications. This method was used in 1791 by J.L Dupain-Treil for a map of France and in 1801 Haxo used it for his projects in Rocca d’Aufo. Thereafter the use of contour lines for cartography became a standard method. The concept of contour lines was used in surveying the mountainside for the experiment. In 1774 conducted the Schiehallion experiment to measure the mean density of the Earth. In 1746 contour lines were used to map land surface by Domenico Vandelli who drew a map of the Duchy of Modena and Reggio. Nicholas Cruquius used isobaths at an equal interval of 1 fathom to draw the bed of the river Merwede in the year 1727, while Philippe Buache used an interval of 10 fathoms for the English Channel in the year 1737. Throughout the 1700s contour lines have been used in numerous charts and maps to illustrate depths and heights of water bodies and landscapes.Įdmond Halley in 1701 used contour lines on a chart of magnetic variation. Contour lines denoting constant depth are now known as “isobaths”. The first recorded use of contour lines were made to illustrate the depth of the river Spaarne located near Haarlem by a Dutchman named Pieter Bruinsz in the year 1584. The use of lines joining points of equal value has been existent since a long time although they were known by names other than contour lines. Equally spaces and evenly spaced lines, it indicates uniform slope. Although the term contour line is commonly used, specific names are often used in meteorology where there is a greater possibility of viewing maps with different variables at a given time. The prefix “iso” can be replaced with “isoallo” which specifies that the contour line joins points where a given variable change at the same rate over a given period of time. Contour lines are often typified with the prefix “iso” which means “equal’ in Greek, as per the type of variable being mapped.
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