<P> A zonal flow regime is the meteorological term meaning that the general flow pattern is west to east along the Earth's latitude lines, with weak shortwaves embedded in the flow . The use of the word "zone" refers to the flow being along the Earth's latitudinal "zones". This pattern can buckle and thus become a meridional flow . </P> <P> When the zonal flow buckles, the atmosphere can flow in a more longitudinal (or meridional) direction, and thus the term "meridional flow" arises . Meridional flow patterns feature strong, amplified troughs of low pressure and ridges of high pressure, with more north - south flow in the general pattern than west - to - east flow . </P> <P> The three cells model of the atmosphere attempts to describe the actual flow of the Earth's atmosphere as a whole . It divides the Earth into the tropical (Hadley cell), mid latitude (Ferrel cell), and polar (polar cell) regions, to describe energy flow and global atmospheric circulation (mass flow). Its fundamental principle is that of balance--the energy that the Earth absorbs from the sun each year is equal to that which it loses to space by radiation . This overall Earth energy balance, however, does not apply in each latitude due to the varying strength of the sun in each "cell" as a result of the tilt of the Earth's axis in relation to its orbit . The result is a circulation of the atmosphere that transports warm air poleward from the tropics and cold air equatorward from the poles . The effect of the three cells is the tendency to even out the heat and moisture in the Earth's atmosphere around the planet . </P> <P> Forcing is a term used by meteorologists to describe the situation where a change or an event in one part of the atmosphere causes a strengthening change in another part of the atmosphere . It is usually used to describe connections between upper, middle or lower levels (such as upper - level divergence causing lower level convergence in cyclone formation), but also be to describe such connections over lateral distance rather than height alone . In some respects, teleconnections could be considered a type of forcing . </P>

What is the relationship between earth's mass and its atmosphere