Answer to Question 1
ANSWER: Multicell thunderstorms may form as a line of thunderstorms, called a squall line. The line of storms may form directly along a cold front and extend for hundreds of kilometers, or the storms may form in the warm air 100 to 300 km out ahead of the cold front.
Answer to Question 2
ANSWER: Beneath an intense thunderstorm, the downdraft may become localized so that it hits the ground and spreads horizontally in a radial burst of wind, much like water pouring from a tap and striking the sink below. Such downdrafts are called downbursts. A downburst with winds extending only 4 km or less is termed a microburst. In spite of its small size, an intense microburst can induce damaging straight-line winds well over 100 knots (115 mph). Microbursts pose an especially serious hazard to aircraft, largely due to the accompanying horizontal wind shear (that is, rapid changes in wind speed and/or wind direction). When an aircraft flies through a microburst at a relatively low altitude, say 300 m (1000 ft) above the ground, it first encounters a headwind that generates extra lift. At this point, the aircraft tends to climb (it gains lift), and if the pilot noses the aircraft downward there could be grave consequences, for in a matter of seconds the aircraft encounters the powerful downdraft, and the headwind is replaced by a tail wind. This situation causes a sudden loss of lift and a subsequent decrease in the performance of the aircraft, which is now accelerating toward the ground.
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