Private Pilot Private Exam

Disable ads (and more) with a membership for a one time $2.99 payment

Prepare for the Private Pilot Private Exam with detailed quizzes featuring flashcards and multiple-choice questions, complete with explanations and tips for success. Ace your exam today!

Each practice test/flash card set has 50 randomly selected questions from a bank of over 500. You'll get a new set of questions each time!

Practice this question and more.

Frost forms under which conditions?

The temperature is above the dewpoint
The temperature of the collecting surface is at or below the dewpoint and below freezing
The temperature of the air is below freezing
The humidity is at 100%

The correct answer is: The temperature of the collecting surface is at or below the dewpoint and below freezing

Frost forms when the temperature of the collecting surface is at or below the dewpoint and below freezing. This occurs because, as air cools, its capacity to hold moisture decreases. When the temperature of surfaces, such as the ground, leaves, or aircraft wings, drops to or below the dewpoint, water vapor in the air can condense and freeze upon contact with these colder surfaces. The presence of freezing temperatures ensures that this condensation turns directly into frost rather than forming dew. In this scenario, the air can indeed be saturated (at 100% humidity), but without the additional condition of the surface being at or below the dewpoint and below freezing, frost will not form. Therefore, the specified conditions are critical for frost formation, making this the correct choice.