Here's Stuart decked out in his very stylish, funny-hat-with-nasal-cannula ensemble, breathing supplemental oxygen while climbing in a thermal over the Big Horn Mountains southwest of Sheridan, Wyoming. We turn the motor off as we reach the mountains and head north-northwest following the high terrain, in smokey haze which is now so thick we can barely make out the valley floor on either side of the range. The lift is good, however, and we quickly reach cloudbase at 16,500' MSL.