The tundra is a biome found in the Arctic and Antarctic regions. The word tundra comes from the Kildin Sami word tūndâr, meaning uplands, treeless mountain tract. Tundras are characterized by permafrost (permanently frozen subsoil), low biotic diversity, limited drainage, and a short growing season. There are two types of tundras: arctic tundras and alpine tundras.
Arctic tundras are found in the northern hemisphere, just south of the ice caps. They are near sea level and experience long, cold winters and short cool summers. The soil is permanently frozen (permafrost), preventing trees from growing. The dominant vegetation in arctic tundras is mosses, lichens, sedges, and grasses. Shrubs may grow in areas with better drainage. Animal life includes caribou, reindeer, muskoxen, lemmings, foxes, wolves, bears, and wolverines. Birds such as ptarmigan and ravens nest on the ground; other birds such as snow buntings migrate to the arctic tundra during the summer months. Insects are active during the brief summer season; they include mosquitoes , flies , beetles , moths , and bees .
Alpine tundras occur at high altitude – above the tree line – in mountains worldwide. They have similar features to arctic tundras but differ in some respects. Alpine soils tend to be dry because of lower precipitation levels; they may also be rocky or sandy. The growing season is shorter than in arctic tundras because of cooler temperatures; however , some plants can flower quickly when conditions are right . Vegetation is sparse but may include grasses , sedges , forbs , dwarf shrubs , mosses , liverworts , and lichens . Animals must adapt to cold temperatures year-round; many migrate to lower elevations during winter . Common animals include pikas , marmots , ground squirrels , hares , weasels , voles mice ) owls
Differential refers to the gears inside a vehicle that allow it to change speed while going around corners without skidding or slipping off course due to centrifugal force.. A Torsen differential uses worm gears to provide torque sensing traction control.. It allows both wheels on an