At what altitude were the wind and temperature reported as 080° at 21 knots and -7°C?

• A. 12,000 feet MSL
• B. 1,000 feet MSL
• C. 20,000 feet MSL
• D. Surface

Answer: (A)

Winds aloft data pair a wind with its actual temperature at specific standard altitudes. The given wind of 080° at 21 knots comes with a temperature of -7°C, and on the winds aloft chart that exact combination sits on the line for twelve thousand feet above mean sea level. The ISA temperature at that level is about -9°C, so -7°C is a plausible value for that altitude, which is why this line is the match. The other listed altitudes would show markedly different temperatures under ISA conditions (for example, much warmer near the surface or much colder at 20,000 feet), so they don’t fit this temperature value. Therefore, the wind and temperature are reported at twelve thousand feet MSL.