Isothern is a line joining places of equal_______?

Step 1: Analyze the question The question asks what an isotherm (written "isothern" in the question, which is likely a typo) joins together on a map.

Step 2: Explain the concept In climatology, the prefix iso- means "equal." The ending tells you what is being measured:

• Isotherm: therm means heat, so it joins places of equal temperature
• Isobar: bar means pressure, so it joins places of equal pressure
• Isohyet: hyet means rain, so it joins places of equal rainfall
• Isoneph: neph means cloud, so it joins places of equal cloud cover
• Isohel: hel means sun, so it joins places of equal sunshine

Step 3: Solve Matching each option to its line:

• A. Cloud cover → isonephs
• B. Pressure → isobars
• C. Rainfall → isohyets
• D. Temperature → isotherms

The word "isotherm" comes from "therm" (heat or temperature), so the answer is D.

Step 4: Answer D. Temperature

Exam tip: Link each root to a word you already know:

• Thermometer → temperature → isotherm
• Barometer → pressure → isobar
• Hyetograph/hydro → rain or water → isohyet

Isotherms are usually drawn on maps after temperatures have been reduced to sea level, so that the effect of altitude is removed.