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## Wind Shear

• Posts: 5

### SteveS created the topic: Wind Shear

Hey everyone,

Got a COLlection of questions...not really just the one. Thought i'd ask it in here for clarification.

Q: Strong horizontal wind shear would most likely be encountered:
A. At a strong surface inversion boundary
B. within a decaying thunderstorm cell
C. Near a low-pressure system
D. In a cirrus cloud

Answer is A, although my reasoning leading me to pick B is that the question states for horizontal wind shear which is the change in wind speed/direction at the same level as opposed to vertical wind shear which is the change of wind direction/speed with height. To experience horizontal wind shear through a surface inversion boundary would mean the aircraft would be climbing through a surface inversion to experience windshear, meaning height was gained and wind speed/direction changed aka vertical windshear. Flying through a decaying thunderstorm cell would mean remaining at the same level while experiencing differing wind speeds through downdrafts aka horizontal windshear.

All help is appreciated. Thanks!

• Posts: 2233

### bobtait replied the topic: Wind Shear

You are correct. That question was amended some time ago. Maybe you don't have the current book.

Wind shear is classified according to the flight path of the aircraft.

Horizontal wind shear is encountered when the aircraft is in horizontal flight and flies through the boundary between air parcels traveling at different vertical velocities (up drafts and down drafts)

Vertical wind shear is encountered when the aircraft is climbing or descending and passes through the boundary of two air parcels traveling at different horizontal velocities. (a surface inversion).

I can understand why some students find that a bit confusing.