By themselves, the drops of water must increase ρ. However, according to the estimation Of appendix A this effect is not significant, which must mean that the drops occupy a very small part of the volume with the rain. The fact that the car does not receive any frontal shock (blow) when it enters a sharply framed region of rain also does not support the assumption that ρ is significantly increased by the rain. The fact that any opposite shock is also never felt suggests that the presence of the gas of H_2 O molecules, which reduces ρ, is also not significant. It is not felt by the driver that the rain changes ρ in any sense. At the same time, figure1is relevant to the distinction in ρ associated with different average temperatures of the air in winter and summer, because a change of the air temperature by 30◦ means [7] a change of the density of the air by about 10%. We have here one more reason why winter is more ‘expensive’ for an individual and the whole nation/country than summer.