What are mode of Spread of Fire ?

CONVECTION: through the motion of heated matter, i.e. through the motion of smoke, air, gases etc. produced by fire.

• The transfer or carries of heat through a liquid or gaseous body such as movement of smoke, hot air and heated gases produced by fire.
• — The replacement of hot and cool air to that particular point resulting in reheated and raised the temperature thus create a fire.

CONVECTION:  The transfer of the heat energy by the movement of heated liquids or gases.

RADIATION:

• heat radiation is the transfer of heat from a source without a material substance being involved.
• Heat radiation is the transfer of heat from a source across the space or travels outward from the fire in  the same manner as light in straight lines to produce vapour and then igniting the vapour.
• — When contacts a body, it is absorbed, reflected or transmitted. Absorbed heat increases the temperature of the absorbing body.
• — Heat radiates in all directions unless it is obstructed

Radiation: The transmission of energy as an electromagnetic wave without an intervening medium