Understanding Isotherms and Other Isolines on Maps

Maps often use lines to connect locations that share a specific equal value for a particular phenomenon. These lines are known as isolines. The question asks for the term used for lines connecting places of equal temperature, specifically when adjusted or "reduced" to sea level.

What are Isotherms?

The term for lines connecting points of equal temperature on a map is Isotherm. The word comes from Greek: "iso" meaning "equal" and "thermē" meaning "heat". Meteorologists and geographers use isotherms to show temperature distribution over an area. Reducing the temperature to sea level helps in comparing temperatures of different locations by removing the effect of altitude, as temperature generally decreases with increasing elevation. This standardization provides a clearer picture of horizontal temperature gradients caused by factors other than height, such as latitude, ocean currents, and land-sea distribution.

Analyzing the Options

Let's look at why the other options are not correct for lines of equal temperature:

• Isoplat: This term is not commonly used to denote lines of equal temperature. It might be related to geological contours of equal values of certain substances, but not temperature.
• Isotim: This term refers to lines connecting points of equal travel time or equal cost in transportation geography.
• Isotac: This term is used in meteorology for lines connecting points of equal wind speed. It can also sometimes refer to lines of equal ice formation.

Based on the definitions, the lines drawn on maps joining places of equal temperature reduced to sea level are correctly called Isotherms.

Conclusion

Therefore, the correct term for lines joining places of equal temperature reduced to sea level on maps is Isotherms.

Revision Table: Key Terms

Additional Information: Types of Isolines on Maps

Maps use various types of isolines to represent different geographical or meteorological data. Understanding these lines helps in interpreting maps and analyzing spatial patterns.

• Isobars: Lines connecting points of equal atmospheric pressure. They are crucial for understanding wind patterns and weather systems.
• Isohyets: Lines connecting points that receive equal amounts of precipitation (rain, snow, etc.) over a specific period.
• Isohels: Lines connecting points of equal duration of sunshine.
• Isonephs: Lines connecting points of equal cloudiness.
• Isobaths: Lines connecting points of equal depth in a body of water (like oceans or lakes).
• Contour Lines (Isohypse): Lines connecting points of equal elevation above a reference point (usually sea level) on land.

Each type of isoline provides valuable information about the distribution of a specific variable across a geographical area.