Cold air is defined as air that has a lower temperature compared to its surroundings. It is denser than warm air, which means it can hold less moisture. This density causes cold air to sink, often leading to weather patterns such as high-pressure systems that can bring clear skies. When cold air moves into an area, it can create a noticeable drop in temperature. This change can affect local climates and weather conditions, leading to phenomena like frost or snow in winter months. Cold air is also essential for various natural processes, including air circulation in the atmosphere.