Warm, moist air from over the ocean moves inland over a city. The moving air mass is blocked by a mountain range. Which type of weather is MOST LIKELY to occur as the warm, moist air meets the mountains? This cold river of air travels from west to east in the northern hemisphere. In winter, it dips south helping to bring cooler air to most parts of the United States. This is the jet stream.

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. 

Answermost of the time it would be ground into fine sediment,and sometimes they are carried away from the original location;

Why the planet stays in orbit is because of inertia (object stays in motion until a force changes it’s motion) also the atmosphere and gravity!