Isohaline
Topic: Graphical Representation of Data and Thematic Maps · NCERT: Class 12, Ch 3 "Graphical Representation of Data"
Meaning
An isohaline is an isopleth, a line joining places of equal value. It joins places where sea water has the same salinity (saltiness). Ocean maps use isohalines to show how salinity changes across seas and oceans. Salinity is higher where evaporation is strong and rain is low. It is lower where rivers, rain or melting ice add fresh water.
Example
Isohaline maps of the seas around India show that the Bay of Bengal is less salty than the Arabian Sea. This is because the Ganga and Brahmaputra pour huge amounts of fresh water into the Bay, while the Arabian Sea loses more water to evaporation.
Don't confuse with
- An isohyet joins places of equal rainfall, not equal salinity.
- An isobath joins points of equal water depth.