Clear a circular area in the snow about 8 feet across.
Using a shovel or snow shoe make a large pile (about 6 feet high) of snow on top of the clearing (the snow should be heaped, not packed.) Mixing snow of different temperatures will facilitate the hardening process.
Allow the mound to freeze and so harden for 1 to 12 hours depending on weather and snow composition. Push sticks 20 – 30cms long into the snow heap, as this will help you to maintain an even thickness over the whole of the shelter when hollowing out. When you find the end of a stick from inside the shelter, you know you have a thickness of 20 – 30cms.
Begin to hollow out the mound once it has hardened sufficiently. Dig straight in at first to create your initial opening, and then dig upward slightly in order to make an elevated sleeping area. This will allow cold air from inside to flow down and out of the shelter.
Use the snow you dig out to make a windbreak in front of the entrance, or heap it onto the exterior of the shelter to thicken its walls and increase the available interior space.
Smooth the interior surface of the walls and ceiling to prevent any melting snow from dripping on you.
Poke a ventilation hole through the top of the dome using a ski pole or long stick. Make sure this hole stays clear of ice and snow.
At this point I usually reduce the size of the entrance hole by packing snow around, but the snow was so powdery, it was impossible to do this. Use your pack or reindeer skin to block the entrance of the shelter once inside, but leave space for air to flow in and out. Keep your shovel inside while you sleep in case you need to dig your way out.
Building a shelter is hard work, so wear the minimum clothing necessary, to reduce the risk of sweating. When you are working you should be cool enough to feel that you need to put another layer of clothing on. Excessive sweating can lead to hypothermia. Once the shelter is completed put all your layers of clothing back on.
Personally, I find this type of shelter hard work and time consuming to construct. The locals just dig a trench in the snow and line it with reindeer skins and sleep in the trench in a sleeping bag. If the air temperature is very cold, they use a stick to prop a reindeer skin over there face to reduce the effect of the cold.