The interpretation of a halo around the moon as a sign of impending rain (or snow) stems from:

Seeing those icy clouds refracting or bending light around the moon means cirrus clouds are present, which might indicate a coming storm.  If you see a halo around the moon on a clear night, it could be an indication that bad weather is moving in.  you're actually just seeing the light of the moon refracting through ice crystals.  They do precede some low-pressure systems by a day or two, and low-pressure systems do bring precipitation storms

Mantle convection is the process that drives plate tectonics. the theory of plate tectonics states that the crust is divided into plates that float on the semi molten mantle below. the circular motion of the magma as it slowly rises and falls or move though convection cells drags the plates along causing them to move. the heat source in the lamp would represent the earth's core. the core is the source of energy that drives convection in the mantle. the lava represents molten magma under the earth's surface. if the lava lamp had floating pieces they would move as the circular motion of the lava in the lamp as it rises and falls would move them along the surface. these floating pieces would represent pieces of the earth's crust. 

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