The word "gradient" refers to the change or difference in intensity, size, or amount of something over a particular distance or time. It is often used to describe how something increases or decreases gradually or progressively. Full definition
Because of their effect on lowering the temperature gradient of the cool skin layer, increased levels of greenhouse gases lead to more heat being stored in the oceans over the long - term. (skepticalscience.com)
The lapse rate sets the temperature gradient of the atmosphere below this height. (92.222.7.6)
This pressure gradient in turn produces a temperature differential on the surface, which prompts production of a tiny electrical current. (sciencemag.org)