While smart bombs provided most of the fire support for American infantry in Afghanistan, artillery was eventually brought in. A battery of 105mm howitzers and two platoons of 120mm mortars showed up. But the Met (meteorological, or weather) platoon was left behind (there being a severe limit to how many U.S. troops could be supported in Afghanistan.) It was thought that the gunners could just use the standard tables for adjusting fire for higher elevations and different temperatures. But it was quickly discovered that the air density in Afghanistan was less than one would normally expect for the high altitudes the troops were operating at (this sort of thing happens in different parts of the world, for various reasons we won't go into here.) The Met platoon could have taken care of the problem, and provided updated adjustments for the firing calculations, but the Met platoon was back in the United States. The atmospheric differences were such that shells were off by several hundred meters at longer (10 kilometers) ranges. But the U.S. Air Force had plenty of meteorological (weather analysis and forecasting) troops in the area. Aircraft are also dependent on air density, temperature and winds. So the army artillery people plugged into the air force meteorological data feed (using the Department of Defense private Internet; SIPR.) A few calculations to adjust between the way the army and air force recorded weather data, and the guns and mortars were accurate again.