Question

isoline a line connecting points of or equal value on a map
isotherm a line connecting points of equal air on a weather map
meteorologist a scientist who studies and forecasts
meteorology the study of atmosphere
radar a device used to determine the location and speed of

Explanation:

• For "isoline", by definition, it connects points of equal quantity.
• For "isotherm", the root "therm" relates to temperature, so it's equal air temperature.
• A "meteorologist" studies and forecasts weather.
• "Meteorology" is the study of the weather (or atmospheric) aspects.
• "Radar" is used for detecting precipitation (common use in weather - related radar).

Answer:

• isoline: equal quantity
• isotherm: temperature
• meteorologist: weather
• meteorology: weather (or atmospheric)
• radar: precipitation