What quality of a surface does 'albedo' refer to?

Albedo refers to the measure of reflectivity of a surface, particularly how much sunlight is reflected by that surface back into the atmosphere. It is expressed as a fraction or percentage, where a surface with high albedo reflects most of the incoming solar radiation, while a surface with low albedo absorbs more solar radiation. For example, fresh snow has a high albedo because it reflects most of the sunlight, whereas dark asphalt has a low albedo because it absorbs more heat.

Understanding albedo is crucial in physical geography as it affects local climate and temperature, playing a significant role in energy balance, surface heating, and the overall dynamics of the Earth's atmosphere. It's also a key factor in studies related to climate change, as changes in land use or cover can alter the albedo effect, impacting global temperatures. In contrast, the other options focus on different physical properties—temperature relates to heat, moisture retention refers to a surface's ability to hold water, and soil composition pertains to the minerals and organic matter present in the soil. Each of these factors is important in its own right but does not define the concept of albedo.