>>1169548>The ground merely stops the heat from leaving as quickly as open air.No, the ground causes conduction to happen between you and the ground. If the ground is colder (which it usually is) than your body, then when you sit or lay on it, the relative temperatures in your body and the ground will try to even out, and because the ground is fucking massive, you'll loose the fight and your body heat.
The wind merely blows away the warmth surrounding your body (created by yourself), but can definitely have a serious effect on heat loss, depending of wind strength and temperature.
Conduction mostly looses heat faster than convection (wind), until a theoretical point where the ground is quite warm and the wind is really cold and really hard.