Colliding air masses within tornado alley make for exceptional conditions that allow for vigorously rising air, which is essential for thunderstorms. Storms in the Great Plains regularly reach 10 miles (16 kilometers) into the sky because of these conditions: 1  Winds pushing disparate air masses converge in tornado alley. 2  Colliding air, known as fronts, have nowhere to go, therefore they rise.
Apple's fiscal 2011 10-K report showed that the average size of an Apple Store has creeped up to 8,400 square feet per store, but Needham & Company analyst Charlie Wolf says that the retail stores are bulging at the seams and just aren't big enough.
Apple (AAPL) has the most successful retail stores by a wide margin. According to RetailSails, a retail and consumer goods consulting firm, the tech giant's 372 worldwide locations sold goods at a rate of more than $6,000 per square foot of floor space in the past 12 months.