Where is a likely location of CAT?

[Ref AC 00-6B, AC 00-30C 6.5] Where is a likely location of CAT? Ans: upwind of the base of the trough on the polar side of a jet stream According to AC 00-30C 6.5: “There are several patterns of upper-level winds that are associated with CAT. One of these is a deep, upper trough. The word “trough” refers to winds that dip southward, then rise northward, forming a trough-like pattern. A “ridge” is the opposite, […]

What’s CAT (Clear Air Turbulence)?

[Ref AC 00-6B, AC 00-30C 6.5] What’s CAT (Clear Air Turbulence)? Clear Air Turbulence (CAT) is a higher altitude turbulence phenomenon occurring (from 20,000 to 50,000 feet) in cloud-free regions associated with wind shear. CAT can occur between the core of a jet stream and the surrounding air. It can often affect an aircraft without […]

What’s the different between “Wind shear alert” and “microburst alert” ? (US)

[Ref US AIM Section 3 Airport Operations 4-3-7] What’s the different between “Wind shear alert” and “microburst alert” ? (US) Ans: “Wind shear alert” is the information from basic LLWAS; “microburst alert” is provided when LLWAS integrated with TDWR. LLWAS (Low Level Wind Shear Alert System) only provides Wind shear alert – wind shear alert […]

What’s the meaning of “terrestrial”?

[Ref Cambridge Dictionary, Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 12-15] According to the Cambridge Dictionary, it means “(of a planet) similar to Earth“/ “relating to the earth“. Rightly, my next question is : What type of fog ALWAYS form over land? Ans: Radiation fog Radiation fog forms when the ground cools rapidly due to terrestrial radiation! Fog

How can we know (calc) the estimated cloud bases? [Dew point Application]

[Ref Understanding Weather & Climate, Books a la Carte Edition (6th Edition) #ISBN-13: 978-0321773227 #ISBN-10: 0321773225 CH 5 Atmospheric Moisture, Pilot’s Handbook of Aeronautical Knowledge, FAA-H-8083-25B Page 12-13] Application of dew point – determine the height of the cloud base Divide the temperature-dew point spread by the convergence rate (2.4ºC or 4.4 ºF), and multiply by 1000 […]

What’s Turbulence?

[Ref AC 00-6B] Turbulence is irregular motion of an aircraft in flight, especially when characterized by rapid up-and-down motion caused by a rapid variation of atmospheric wind velocities. 3 major causes (types) of Turbulence convective currents : called convective turbulence obstructions in the wind flow : called mechanical turbulence (e.g Mountain Wave) wind shear   […]

Where can we expect “fair weather cumulus”?

[Ref AC00-6B] “fair weather cumulus” is a kind of Cumulus with little vertical development. The formation of the cumulus with little vertical development related to convective currents. Day time – sea breeze – over lands Night time – land breeze – over water bodies Over land, on clear mornings, cumulus may form as the sun […]

What can you expect in Cumulus Cloud (Cu)?

[Ref AC00-6B] What can you expect in Cumulus Cloud (Cu)? Indeed, there are 2 types of Cumulus Cloud (Cu): Cumulus with little vertical development (e.g fair weather cumulus) Towering cumulus (TCU)   For Cumulus with little vertical development: turbulence Note: suppose no significant icing!   For Towering cumulus (TCU) – cumulus with moderate/strong development: very […]