Which term refers to resources that must be used as they occur, such as sunlight and wind?

The term that refers to resources that must be used as they occur, such as sunlight and wind, is flow or natural resources. These resources are characterized by their naturally occurring and transient nature, meaning they are constantly replenished and are available only during specific times or conditions. For instance, sunlight is available during the day and wind occurs when atmospheric conditions are right, making them inherently different from resources that can be extracted and stored for use at a later date.

In contrast, other resource categories, such as renewable resources, encompass a broader range, including those that can be replenished over time, but may not necessarily be available continuously like flow resources. Non-renewable resources typically refer to fossil fuels or minerals, which cannot be replenished once depleted. Exhaustible resources are those that can be used up entirely and typically do not fall under the category of resources that can be continuously harnessed as they appear.