Just like contours that show areas on a map with the same altitude (height above sea level), isotherms are used to show areas with the same temperatures in the atmosphere. Isotherms relate to isobars (that join places with same pressure) – because temperature and pressure are inversely related.
The isotherms on a map show the areas with the same temperature levels.
<u>Explanation:</u>
Isotherms are the lines that join the points of the same temperature on a map.
In other words, an isotherm of a specific temperature level passes through areas that reflect the temperature identical to the temperature of the isotherm.
The functioning of the isotherm lines is similar to that of contour lines. Isotherm lines prove beneficial in the determination of relative temperature variations and other meteorological applications.
I would choose D as they both have weather greatly effected by mountain ranges although A my seem like the answer some southern regions of the Midwest are very hot.