Actually, it does not "require" warm air - it just rises quicker in a moderately warm environment. But it would still rise in an normal temperature room, it just takes slightly longer. However longer rising times at lower temperatures are quite beneficial to the taste of the bread; the longer the rising time, the more acetic acid builds up in the dough, giving it a characteristic "bread" taste.
Warm air will rise.
It is the warm air
When warm air overtakes cold air, it rises and forms an unstable atmosphere. The warm air will continue to rise due to its lower density, creating clouds and potentially causing precipitation. This process is known as atmospheric instability.
Cold air is more dense than warm air. If flows beneath the warm air and forces it to rise.
the yeast respire in warm conditions (proving - when you put in under a tea towel in a warm place) during repiration they make c02 which leaves little air pockets these harden because of the gluten when baked to make the bread airy and risen so basically - make the bread rise
lighter
yes
Thunderstorms require warm, moist air to rise and create the conditions for lightning. If the temperature is below freezing, the air is too cold to rise and create the necessary instability for thunderstorms to form. Additionally, the lack of sufficient moisture in the atmosphere at colder temperatures can also inhibit the development of thunderstorms.
Warm air rises. Cold air sinks.
When warm air rises, bubbles of gases dissolved in liquids such as water or soda can also rise to the surface. This is because warm air is less dense than cool air and can carry lighter objects, like bubbles, upwards.
A warm air mass rises over a cold air mass at a warm front because warm air is less dense than cold air. This results in the warm air mass being forced to rise and cool, leading to the formation of clouds and precipitation at the boundary of the two air masses.
so that the bread will riseBread yeast is a type of fungi that reproduces by a process called budding. This process causes it to release carbon dioxide which gets trapped in the dough.