We asked a pilot to explain how high planes fly and why they need to maintain cruising altitude. Here's what he had to say.

Can planes fly in negative temperatures ... can drop precipitation as high as 23,000 feet, but above this, clouds are very sparse. “Jetliners tend to fly above the clouds to avoid weather ...

Some people enjoy watching clouds, but I prefer contrails ... I recently took a photo of a trail following a plane flying above the Sutro Tower, rising from the city’s heart.

For Joe Parente, the sky was never the limit. For him, it was home.  From a childhood fascination with airplanes to a career ...