Does heat travel in waves

Answer 1

heat can not travel downwards because particles that are heated take up more space because they are faster than other particles this means that they are less dense so they travel up just like how a cork travels up when it is placed in water, because the cork is less dense than water.

Answer 2

Yes, heated air rises. the hot air molecules have the same mass as the cold air particles, but they are less dense (the "hot molecules" that move more quickly expand into a larger volume, so hot air will move to areas of low pressure allowing such expansion). The farther away from earth, the less dense/pressured the molecules are, because like all molecules, the air molecules have weight and will fall. however, heat per se simply radiates in all directions.

Answer 3

This is a complex question since heat travels in many different forms.

I will focus on heat transmission in solid crystals, that is the less complex case. The atoms at the nodes of the crystal vibrates in three dimensions around their stable position, that is the crystal node. The energy associated to this vibration is the temperature.

When heat propagates through the crystal, nearby atoms influences each other through the crystal constituting bonds and exchange vibrational power. The exchanged power, that is heat, propagates through the crystal in a sort of high frequency waves called phonons. Thus, if you look at it under a microscopical point of view, heath is exchanged in a crystal through local waves.

If you look the phenomenon under a macroscopic point of view however, the random nature of this huge number of microscopic waves generates the fact that the wave nature is lost and you see the average result of propagation. This can be described macroscopically with the so called heat transmission equation that is not a wave equation, but a diffusion equation. Thus, if you look the phenomenon macroscopically heat diffuses in a crystal. Diffusion is characterized by a progressive and isotropic propagation, differently from the oscillating nature of waves, that in our case averages out due to their randomness.

Its a little tricky, but nature is tricky you know, otherwise science would be annoying :-)