What are the two requirements for long-range spotting in wildland fires?

Long-range spotting in wildland fires occurs when embers or firebrands are carried away from the main fire by environmental factors, leading to the ignition of new fire areas at a distance from the original fire. The two key requirements for this phenomenon are wind and a well-developed convection column.

Wind plays a crucial role in transporting the embers from the fire. It helps lift burning embers into the atmosphere, where they can be carried over considerable distances. Without sufficient wind, the embers may not travel far enough to ignite new fires.

A well-developed convection column is equally important because it creates a structured upward movement of hot air and gases from the fire. This convective activity can contribute to the formation of turbulent air patterns that further assist in casting embers aloft, increasing the potential for spotting.

The other options do not encapsulate the essential dynamics needed for long-range spotting. Low humidity may relate to fire behavior but does not directly facilitate the spotting process. Low temperatures would hinder fire spread and ember production, while high humidity is generally unfavorable for fire growth and ember activity.