Forecast icing conditions occur under which temperature range with visible moisture?

Forecast icing conditions occur under which temperature range with visible moisture?

• A. -10 to -40 degrees Celsius with no moisture
• B. +02/-10 degrees Celsius with visible moisture (clouds, fog, rain, sleet)
• C. 0 to +5 degrees Celsius with dry air
• D. +20 to +30 degrees Celsius with hail

Answer: (B)

Icing requires two things: visible moisture in the air and a temperature where moisture can freeze on contact with the aircraft. When you have visible moisture such as clouds, fog, rain, or sleet, and the air temperature sits around freezing or slightly below (roughly from about 0°C down to -10°C, and extending into the subfreezing range), supercooled droplets can strike the aircraft and freeze on impact, building ice rapidly. The option that mentions temperatures around 0 to -10°C with visible moisture best fits that condition, because it combines both needed factors—visible moisture and subfreezing air—allowing icing to form. The other choices fail because either there is no visible moisture, or the air is dry, or the temperature is well above freezing, where icing is not produced by supercooled droplets.

Icing requires two things: visible moisture in the air and a temperature where moisture can freeze on contact with the aircraft. When you have visible moisture such as clouds, fog, rain, or sleet, and the air temperature sits around freezing or slightly below (roughly from about 0°C down to -10°C, and extending into the subfreezing range), supercooled droplets can strike the aircraft and freeze on impact, building ice rapidly.

The option that mentions temperatures around 0 to -10°C with visible moisture best fits that condition, because it combines both needed factors—visible moisture and subfreezing air—allowing icing to form. The other choices fail because either there is no visible moisture, or the air is dry, or the temperature is well above freezing, where icing is not produced by supercooled droplets.