This is a lava lamp. when the light bulb heats the wax, the wax rises. when the wax cools, it falls. this cycle of rising/falling is an example of:

this is an example of Convection

explanation:

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

most community's take hundreds of years to become stable