80 likes | 213 Views
Temperature Inversions in Alaska ITEP Air Quality Training Lower Kalskag 2014. Barbara Trost/Bob Morgan Alaska Department of Environmental Conservation. Normal Conditions. Warm air rises | cold air sinks Temperature decreases as you go higher in atmosphere Warmer near ground, colder aloft
E N D
Temperature Inversions in AlaskaITEP Air Quality TrainingLower Kalskag 2014 Barbara Trost/Bob Morgan Alaska Department of Environmental Conservation
Normal Conditions • Warm air rises | cold air sinks • Temperature decreases as you go higher in atmosphere • Warmer near ground, colder aloft • Mixing between air at low and high levels
Temperature Inversion • After sunset, ground loses heat quickly • Air above ground stays warmer • Colder air at surface is trapped under warmer layer • Temperature profile of atmosphere is inverted • Inversion dissipates after sun heats up ground & wind mixes air between ground and above surface
Temperature Inversions (cont.) • Occurs in morning after earth has lost all heat from sun overnight • Calm winds, clear skies • Coldest places are lowest points, such as valleys and frozen rivers beds
Seasonal Factors • Occur year-round, but strongest in winter • Alaska experiences extreme winter inversions compared to lower 48 • Can be very shallow - ~20 feet • Temperature difference of 20° over 100 feet of elevation Stack is above inversion inversion Stack is below inversion
Health Impacts • Can impact public health • Steam/smoke from smokestack rises and flattens out, trapping pollution in shallow layer above surface • Traps other pollutants, such as Carbon monoxide from vehicle exhaust or particulate matter from residential wood burning • Very cold air makes it difficult to breathe • Ice fog