Thats not smoke - its cool vapour

2.1 Understanding fuel

It is worth noting that wood contains three main components that we are interested in
Water
All wood contains water. Green wood contains a lot, dry wood less. But it all has some.
Cellulose .– Tree cells are made of cellulose. When cellulose is heated it changes. Up to about 200 centigrade, carbon dioxide and water vapour are given off. Above this temperature, pyrolysis takes place. In this process, volatile gases are given off that catch fire. These burning gases give off heat causing a chain reaction and the fire gets hotter. The fire gets hotter and at 450 centigrade, the carbon left behind by the pyrolysis starts to burn. The wood goes through three stages burning
A. “Smoking” stage as the water and CO2 are driven off,

B. “Flame” in which the volatile pyrolysis gases are driven off, burn, and raise the temperature

You can see how the flame is actually gas.

C. “Carbon burn” in which the fire reaches a high enough temperature to generate glowing embers.

Wood can be converted to carbon (charcoal) by heating it without oxygen. This prevents the pyrolysis gases igniting

The glowing coal as the major heat source

2.2 Understanding Heat

It is worth explaining that in the process of combustion, heat is both an input and an output. Heat exists in combustible material (fuel) in the form of

chemical potential energy. That is to say that energy is stored in the chemical components of the fuel and can, given the right circumstances, be

released. We all know this – you burn wood to generate heat. Heat is also an input in that for the process to take place, the right materials must be present and the temperature raised to the point at which the reaction begins. This is known as the process of ignition. In burning wood, we raise the temperature of the wood to initially drive out water and then to the point at which the gases being to burn. This releases more energy that causes the carbon to burn.

Can you see the water bubbling out of the tinder?

This explains why it is in some ways easier to light dry wood than charcoal – there are no pyrolysis gases in charcoal to burn. However since charcoal also doesn’t need to have the water driven off, whilst the temperature needs to be higher, the actual amount of energy that needs to be expended may be lower. We’ll come to that.

Now its important to understand two things here:

The amount of input energy required to achieve is proportional to the amount of material being heated. It takes more energy to raise the temperature of a larger object. If the same amount of energy is input to a large object as a small one, it will raise the temperature less – possibly below the point of combustion. So its easier to light small things than large ones!
When an object is heated to a point beyond its surroundings, it will begin to lose heat to its surroundings (through a variety of mechanisms such as convection and conduction). If an object is heated too slowly, it will lose heat at an equivalent rate and never achieve ignition.

(Bluffers Guide)
You have to heat up wood to get it to burn. The bigger it is, the more heat this will take. The wetter the wood is, the more heat this will take. You have to heat carbon fuel (charcoal etc.) to a higher temperature than wood to get it to burn (which takes more heat) but you usually don’t have to drive the water off (which takes less heat)

2.3 Understanding Air

It is worth understanding that the available oxygen usually limits the process of combustion. Adding oxygen will often cause a fire to burn hotter and faster – the process that makes blacksmiths bellows work. This must be tempered with understanding that you can blow the fuel away. In blowing out a candle, the gas (vaporised wax) is removed from the heat source and the candle goes out. Blowing hard on glowing charcoal will make it burn faster since the charcoal is unlikely to blow away. Blowing too hard when fuel is flaming (burning vaporised hydrocarbons) may extinguish it, blowing on glowing coals probably wont.

Now air can be added to the mix in a variety of ways – by blowing, through mechanical means (bellows or fanning) or via scientific principles. Let’s take one of the most useful. The chimney. Heat rises. We know this right? So as a fire burns, the hot gases and vapours will rise up a chimney. This draws more oxygen into the fire at the bottom. In addition, if a wind is passing over a chimney, it lowers pressure. This lower pressure makes the chimney draw still more gas up through it and hence oxygen into the fire.

(Bluffers Guide)
All fires need oxygen. Forcing oxygen onto a fire based on gas risks blowing it out. Forcing oxygen into a carbon-based fire will probably increase it temperature. The best way to feed oxygen into a fire is to draw oxygen up through it (in the same way as a chimney does)

A hollow elder tube used to blow air into a fire.