In climatology and weather mapping, an isoneph is a line drawn on a map joining places that have equal values of which of the following elements?

Introduction / Context:
Meteorological and climatological maps use different types of lines to represent equal values of specific atmospheric elements. Each type of line has a distinct name, and exam questions frequently test whether candidates can correctly match these names to the phenomena they represent. An isoneph is one such term related to clouds.

Given Data / Assumptions:
• The term under consideration is isoneph. • Options mention cloudiness, salinity, temperature and pressure. • We assume standard meteorological terminology where iso means equal and the root word indicates the mapped variable.

Concept / Approach:
Isoneph is derived from Greek roots meaning equal cloud. It denotes a line on a weather map that joins places with equal amounts or degrees of cloud cover. Other familiar terms such as isotherm, isobar and isohaline refer to equal temperature, pressure and salinity respectively. Recognising these root words helps in remembering their meanings correctly.

Step-by-Step Solution:
Step 1: Break the term isoneph into iso, meaning equal, and neph, relating to clouds. Step 2: Recall that meteorologists use isonephs to show patterns of cloud cover at a given time or averaged over a period. Step 3: Match this understanding with the options and identify cloudiness as the correct choice. Step 4: Eliminate other variables like salinity, temperature and pressure, as different iso terms are reserved for those.

Verification / Alternative check:
Standard geography and meteorology glossaries define an isoneph as a line connecting places with equal cloudiness or cloud cover. The same sources define isotherms for equal temperature, isobars for equal pressure and isohalines for equal salinity, which confirms that isoneph is linked specifically with clouds.

Why Other Options Are Wrong:
Option B (Salinity) is mapped using isohalines or similar terms, not isoneph. Option C (Temperature) uses isotherms, which are widely known from weather maps. Option D (Pressure) uses isobars to connect points of equal atmospheric pressure.

Common Pitfalls:
• Learners sometimes confuse the many iso terms and may choose temperature or pressure if they are more familiar with isotherms and isobars. • Others may not break down the word isoneph into its Greek roots and therefore guess based on intuition rather than recognising the cloud related root.

Final Answer:
An isoneph is a line joining places of equal cloudiness.