What is the main characteristic of medium fuels?

The main characteristic of medium fuels is that they typically range from 1 to 3 inches in diameter. This classification plays a significant role in understanding fire behavior, as medium fuels can sustain combustion with a sufficient surface area to support flames while not being so large that they are slower to ignite or require more energy to burn. These fuels include small shrubs and young trees, which can contribute to fire spread under certain conditions.

In contrast, fuels that are less than 0.25 inches in diameter are classified as fine fuels, known for their quick ignition and rapid burning characteristics. Fuels that are more than 3 inches in diameter are generally categorized as heavy fuels, which tend to burn more slowly and may require a longer duration of heat to sustain combustion. Grass alone constitutes a different category of fuel, primarily known as fine fuels, which burn rapidly due to their small size and lower moisture content.