What does 'environment lapse rate (ELR)' refer to?

The environment lapse rate (ELR) is a vital concept in meteorology that describes how temperature changes with altitude in the atmosphere. The correct definition pertains to the variation of temperature at different heights in a specific location and over a specific time, which aligns with the idea that ELR measures the overall trend of temperature decrease as you ascend into the atmosphere.

When examining the other choices, the temperature change at higher altitudes describes the phenomenon but does not capture the aspect of location and time specificity, which is critical for defining ELR accurately. The reference to a steady horizontal air mass pertains more to the concept of adiabatic lapse rates rather than the environmental conditions at a given location. Finally, focusing on temperature trends in storm systems is too narrow, as ELR encompasses broader atmospheric conditions beyond just storm systems. This comprehensive understanding emphasizes why the definition focusing on variation in a specific location and time is the most precise understanding of the environment lapse rate.