That refers to radiation.
Radiation
Radiation.
radiant For one thing, it's how heat energy from the sun reaches us.
I assume you mean heat transfer. The answer is radiation.
Heat transfer by means of radiation doesn't heat the medium. In fact, radiation doesn't even require a medium in order to work. Strictly speaking, convection doesn't heat the medium either. Convection transfers heat by moving the medium around. Of course, heat also spreads throughout the medium by conduction while the convection is going on.
Infrared radiations. They do not require any medium. So they don't heat any medium. They don't even heat the air through which they pass.
Radiant heat (electromagnetic waves) does not require a medium. Sunlight, infrared light, microwaves are all radiant heat in the form of electromagnetic radiation.
Both conduction and convection require an intervening medium, but convection requires the medium to be able to move.
radiant For one thing, it's how heat energy from the sun reaches us.
heat transfer
I assume you mean heat transfer. The answer is radiation.
Heat transfer by means of radiation doesn't heat the medium. In fact, radiation doesn't even require a medium in order to work. Strictly speaking, convection doesn't heat the medium either. Convection transfers heat by moving the medium around. Of course, heat also spreads throughout the medium by conduction while the convection is going on.
Infrared radiations. They do not require any medium. So they don't heat any medium. They don't even heat the air through which they pass.
Due to nuclear reaction in the sun it emits enormous heat ,and heat does not require any medium to transfer.
Radiation in heat transfer is one of three known modes of heat transfer: conduction (as heat transfer in solids and less effective in liquids)), Convection (as in liquids and gases), and radiation (that not necessarily require a medium for the transfer). Heat of sun is transferred to us in the vacuum space by radiation heat transfer.
Radiant heat (electromagnetic waves) does not require a medium. Sunlight, infrared light, microwaves are all radiant heat in the form of electromagnetic radiation.
It require the medium with conduction property. The medium must be stable enough to withstand heat and not thermally decompose. It is then apply temperature difference to start such conduction heat transfer.
Insulation is not a method of heat transfer.
In order for heat to transfer by convection, there has to be air or water in order for the molecules to move from place to place. So both these heat transfer techniques require a medium of some sort. In a vacuum, there's no particles at all, so there is no medium present in order for these heat transfers to apply.