The rate of heat loss also depends upon the surface area exposed to the fluid. In this case, the surface is the skin, and the surface area of our skin is about 2 square meters. Convective heat loss can be reduced by wearing wind-proof garments and a hat. Radiation is the method by which the sun heats the earth. In this case, energy is transmitted as electromagnetic waves, without any direct contact of the surfaces or exposure to any heat transfer fluid.
Thermal energy is radiated primarily at infrared wavelengths.
You can experience radiative heat transfer by holding your hand facing a bright light bulb. Without contacting the bulb, and even if there is a slight breeze blowing from your hand to the light, you can feel the heat on your hand. This is also why the side of a house sitting in the sun all day feels warm, even if you don't touch it. Again, clothing can help minimize heat losses by radiation. Energy can also be transferred by a phase change in a material.