For the last few days on the news there has been much discussion on the nature of forest fires and how they spread (August 2016). Repeatedly it has been stated that it is unknown how they can spread so quickly. Using a thought exercise as applied to the physics of water I have an idea.
Water is comprised of oxygen and hydrogen. As most know hydrogen is highly combustible and is used as a fuel. Now to the nature of water molecules, a tree pulls water from the ground by its vast root system and into its trunk and then branches and lastly it is sent to the leaves. As the water makes the trip up to the leaves the pathways narrow until the water molecules are nearly single file. However the molecules are still bonded together through adherence. Thereby the water molecules at the top of the tree are connected to the water molecules still in the root system. Turning now to the root system, the root system of many forest trees are symbiotic, they share a bond with all other trees. In a forest the root systems of trees are interconnected thus sharing water molecules.
A fire starts in a small patch of trees. Quickly the fire rises in temperature, this increase in temperature it transmitted to the internal part of the tree, heating the water molecules. In turn the molecules start to vibrate rapidly soon in a few molecules the oxygen molecule has separated from the hydrogen molecule. That hydrogen molecule then starts a chain reaction throughout that tree, into its root system and into the root systems of nearby trees. Remember we are speaking only of a vibration frequency required by the temperature to separate the molecules. Once enough hydrogen molecules are separated several scattered trees become sitting bombs waiting for the slightest change in temperature to ignite. So a patch of trees a few feet away could appear safe, yet inside the chain reaction is already taking place. Thus some trees simply explode, sending fragments of itself everywhere, others appear to just spontaneously combust without any nearby trees being on fire.
It is possible that a forest fire is not spreading above ground, but the spread my in fact be happening under ground through the root system and the sharing of water molecules, namely hydrogen once separated.
If that were the case logically cooling trees several feet away or digging trenches below the root line, cutting the shared massive root system may stop the chain effect.
Example, a fire erupts in a one mile area. Instead of starting the fight in that area extend to an addition half mile beyond and trench the ground below all root systems about 200 feet wide, removing all trees in the dead zone that is being created. When a fire jumps a road, the internal temperature of the trees on the opposite side is already at combustion level due to the sharing of water molecules in their underground root system under the road. If that root system is trenched underground then trees 200 feet away will not increase in temperature inside. So a trench half a mile from the fire line and 200 feet wide may act as a dead zone.
Of course this does not account for above ground wind feed pushing.