Visibility Flashcards
What is Prevailing Visibility?
It is the maximum visibility common to sectors comprising of half or more of the horizon circle. Provided in SM
What is RVR a measure of?
The maximum distance in the take-off or landing direction runway lights can be seen.
What three factors must be known to calculate RVR?
Visibility provided by forward scatter meter
Ambient light level
Runway light intensity
What is slant visual range?
Maximum distance light can be seen while landing.
What are lithometeors?
Dry particles suspended in the air, includes haze, smoke, sand and dust.
Where is haze most common?
Lower thousand feet
Dense haze may reduce visibility to less than?
3 miles
Smoke becomes concentrated in the lower levels when what happens?
A low-level inversion
What heights can sand and dust be lifted to?
Sand: 50-100 ft
Dust: 10 000 - 15 000 ft
Which of the following reduce visibility the most to least: drizzle, rain and snow?
Snow> Drizzle> Rain
Rain seldom reduces visibility below one mile, except when?
Brief heavy showers
Why does drizzle reduce visibility more than rain?
It falls in stable air and is frequently associated with fog or smoke.
Blowing snow is usually confined to what heights?
100 - 300 ft
Fresh snowfall and brisk winds can reduce surface visibility to?
Less than half a mile
What are the requirements for fog?
High relative humidity, abundance of condensation nuclei and method to increase relative humidity.
