Hot air is less dense than which type of air?

Hot air is less dense than cold air because density is influenced by both temperature and pressure. When air is heated, the molecules within it move more rapidly and space out more, leading to a decrease in density. This principle is a fundamental concept in thermodynamics and fluid dynamics.

In contrast, cold air, being denser, has molecules that are more closely packed together. As a result, when warm air rises, it displaces cooler air, demonstrating the phenomenon of convection. This behavior is critical in weather patterns and understanding how heat travels in the atmosphere.

The other options, warm air, dry air, and moist air, do not exhibit lower density than hot air. Warm air is, by definition, at a higher temperature than cold air but is denser than hot air; dry and moist air can vary in density based on humidity and temperature but still do not represent a lower density than hot air under typical conditions. Consequently, the correct understanding is that hot air is indeed less dense than cold air.