Aviation Weather Exam Studyguide 2023

What are the characteristics of the flow of air around high pressure systems? - ANSWER Outward Downward Clockwise What are the characteristics of the flow of air around low pressure systems? - ANSWER Inward Upward Counterclockwise What is a Trough Line? - ANSWER An elongated area of low pressure. (Air rises in this area) (It is conducive to cloudiness and precipitation) What is a Ridge Line? - ANSWER An elongated area of high pressure. (Air moving out of a high depletes the quantity of air - therefore these are areas of descending air.) (Descending air favors dissipation of cloudiness) What are isobars? - ANSWER Lines on a weather chart which connect areas of equal or constant barometric pressure. If isobars are close together on a weather chart or a constant pressure chart what does this mean? - ANSWER This shows the steepness of the pressure gradient. • Close = Steep Pressure Gradient = High Wind Speeds • Spaced Out = Shallow PG = Low Wind Speeds What causes the winds aloft to flow parallel to the isobars? - ANSWER Coriolis Force What causes surface winds to generally flow across the isobars at an angle? - ANSWER Surface FrictionWhat is the effect of stable air on clouds? - ANSWER Stratiform What is the effect of unstable air on clouds? - ANSWER Cumuliform What is the effect of stable air on turbulence? - ANSWER Smooth What is the effect of unstable air on turbulence? - ANSWER Rough What is the effect of stable air on precipitation? - ANSWER Steady What is the effect of unstable air on precipitation? - ANSWER Showery What is the effect of stable air on visibility? - ANSWER Fair to Poor What is the effect of unstable air on visibility? - ANSWER Good At what rate does atmospheric pressure decrease with an increase in altitude? - ANSWER 1in. Hg per 1,000 ft. How do you determine the stability of the atmosphere? - ANSWER By observing the actual lapse rate and comparing it to the standard lapse rate of 3.5° F (2° C) per 1000 ft. (In general stable air cools at a rate less than the standard lapse rate with altitude) The "K" index of a stability chart is the primary means of determining stability. What are the stages of a thunderstorm?