Covering the bases.(Banc One Ballpark, Phoenix, Arizona)

Stadium's retractable roof and air conditioning help baseball fans keep their cool

With the break of day, sunlight floods the interior of Bank One Ballpark (BOB), providing the stadium's natural grass field with its needed ultraviolet rays. By 3 p.m., as the temperature in Phoenix soars to nearly triple digits, a stadium employee pushes a button to close six operable telescoping roof panels and seal the park from further heat gain. For the next four hours, an 8,000-ton cooling system reduces the temperature to a comfortable 72 degrees.

At 7 p.m., as the Ariz