This wind tunnel design pdf a good article. Follow the link for more information. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with change in altitude.
Horizontal wind shear is a change in wind speed with change in lateral position for a given altitude. Wind shear has significant effects on control of an aircraft effect, and it has been a sole or contributing cause of many aircraft accidents. Wind shear is sometimes experienced by pedestrians at ground level when walking across a plaza towards a tower block and suddenly encountering a strong wind stream that is flowing around the base of the tower. Sound movement through the atmosphere is affected by wind shear, which can bend the wave front, causing sounds to be heard where they normally would not, or vice versa. Wind shear refers to the variation of wind over either horizontal or vertical distances.
Vertical speed changes greater than 4. Wind shear is also a key factor in the creation of severe thunderstorms. Note the downward motion of the air until it hits ground level, then spreads outward in all directions. The wind regime in a microburst is completely opposite to a tornado.
Vertical wind shear above warm fronts is more of an aviation concern than near and behind cold fronts due to their greater duration. When a nocturnal low-level jet forms overnight above the Earth’s surface ahead of a cold front, significant low level vertical wind shear can develop near the lower portion of the low level jet. This is also known as nonconvective wind shear since it is not due to nearby thunderstorms. The change in wind can be 90 degrees in direction and 40 kt in speed. It tends to be strongest towards sunrise.