There are 4 types of heat loss:
Conduction occurs from contact with a colder surface and is dependent on the material involved. Some substances conduct far more than others. For example water conducts 24 times more than dry air.
Convection occurs when a fluid (liquid or gas) changes density because it is warmed. The lower density fluid rises above colder, more dense, fluids and circulates heat away. Forced convection, as in a fan oven, moves a fluid for quicker heat transfer. Wind Chill is a good example.
Evaporation is when a liquid changes to a gas, requiring a massive heat input. For example evaporating water requires approximately 540 times more energy than raising its temperature by 1'C (depending on exactly what the ambient temperature is). Wind Chill also increases evaporation by reducing the pressure at the surface.
Radiation can occur across a vacuum and accounts for enormous heat loss. It is dependent on the qualities of the surfaces involved and is proportional to the difference in the fourth power of the temperatures (according to Stephan's Law).
Water Chill is a term that explains the impact of water on cooling. It involves conduction, convection and evaporation to have an enormous effect, especially when combined with Wind Chill.
Water Chill is useful to keep us cool, which is why we sweat, but at the same time our outdoor clothing must protect us from its worst effects. FurTech products achieve a balance in breathability and waterproofing in order to maintain a stable body temperature.
The Blizzard Reflexcell products are one of the few effective survival products as they slow evaporation from damp inner layers, form a waterproof and windproof barrier, add a layer of dry air to limit conduction and reflect radiative heat. Though they insulate from the ground better than other products it's still better to use them with a foam pad.
Adding a Shelter keeps wind and water at bay and creates an environment where you can sort out your kit.