英语翻译Convection is the transfer of heat from one place to ano

英语翻译
Convection is the transfer of heat from one place to another within a liquid or gas by mixing one part of liquid or gas with the other.It could be defined as the process by which gases and liquids move about,due to changes in temperature and pressure.A gas or liquid expands when heated.It becomes lighter and moves upward as gravity pulls the heavier,less heated gas or liquid downward.The transfer of heat by convection is used both in heating and in cooling our homes.
A steam radiator is a good example of heating by convection.Air in contact with the radiator warms and rises because it is lighter than the other air in the room.It is displaced by cooler air.
Radiation is the transmission of heat from a heated body to cooler body by heat waves or the transfer of heat by electromagnetic waves.Similar to radio signals,radiation can transfer energy through empty space.Unlike conduction and convection,radiation does not require a substance to transfer heat.
The heat we get from the sun is an example of radiation.Another example is warming one's self by an open fire.The side next to the fire gets warm while the opposite side remains cool.Turn around and the cool side warms up and the warm side cools off.Since you are not actually touching the fire,this warming cannot be by conduction.Likewise,it cannot be heat transmission by convection for only the side next to the fire is warmed.If it had been heat by convection the both sides would have been warmed.