An isothermal layer is a layer in which:

• A. Temperature increases with height
• B. Temperature decreases with height
• C. Temperature is constant with height
• D. Temperature varies significantly

Answer: (C)

An isothermal layer is characterized by a consistent temperature throughout its vertical extent, meaning that the temperature does not change with height. This distinct property is significant in atmospheric science because it can impact the stability of the atmosphere and the behavior of different weather phenomena.

In a situation where the temperature is constant, there are no lapses or inversions concerning thermal stratification within that layer. This can lead to unique conditions, such as trapping pollutants or moisture, potentially affecting visibility and the development of clouds.

The other choices do not accurately describe an isothermal layer. In layers where temperature increases with height, we typically refer to those as inverted layers, while layers with decreasing temperature are described as a normal lapse rate. Variations in temperature indicate dynamic atmospheric conditions that are fundamentally different from an isothermal scenario. Understanding these distinctions is critical for interpreting meteorological data and forecasts accurately.