there must be a double coincidence of wants, and the elements of the desired trade must be of equal value.
rturt
Heat is a transfer of energy from one object to another due to a difference in tempurature.
Two things: 1) the air must reach dew point temperature and 2) there must be some kind of tiny particles in the air called condensation nuclei for the moisture to condense upon.
When a cell does not have enough oxygen for respiration is when fermentation occurs.