But convection currents are ultimately at the mercy of temperature differences because these are what create pressure differences in the first place. The pressure difference between two locations is called a pressure gradient, and the force that actually moves air as wind is called the pressure gradient force.
oÂ·nus. n. 1. A difficult or disagreeable responsibility or necessity; a burden or obligation. 2. Responsibility for an error or fault; blame: Each side wants to avoid the onus of having started the disagreement. 3.
humus. n. 1. (Biology) a dark brown or black colloidal mass of partially decomposed organic matter in the soil. It improves the fertility and water retention of the soil and is therefore important for plant growth. [C18: from Latin: soil, earth].