Constant Height - 12000 ft -12 hr
This is a set of upper air charts for various flight levels primarily for aviation concerns. The plots include plotted data, temperatures are contoured in yellow, and wind speeds are contoured in blue. Increasing speeds are highlighted in varying shades of blue. The lowest speeds are not shaded. Above a certain level, the winds are shaded in alternating dark blue stippled and solid blue on 20 knot levels. The lowest level of shading is 30 knots for 3, 6, 9 and 12 thousand feet. It is 50 knots at 18 and 24 thousand feet and 70 knots at 30 and 36 thousand feet.