Do Sunsets Cry?

It was late at night, but all he could think of was that one question, that had buzzed in his head even as Amelie Poulain found her love, only to become a scooter freak:

What is the air pressure in Pascal on a day in Autumn when the sun sets at around 5.20pm in bristol?

He could think of no other thing. He looked up Pascal, atmospheric measurements of all kinds, trying desperately, and with the help of two dosages a day of Ginkgo Biloba to remember high school physics and also that long lost university physics knowledge at the back of my mind, slowly replaced by useless computer facts and location of this or that minidisc from some freeform jam. But it couldn't help. He had to resort to the immense brain of the world's interconnected computers. He typed it in:

It read: [The dominion of the air]

A single link. Only one book tackled all the subjects that were contained in his question. It spoke of Bristol, and days in Autumn and air pressure, and sunsets, and the time when the train used to go by. He began to read:

 CHAPTER I.  THE DAWN OF AERONAUTICS.

 "He that would learn to fly must be brought up to the constant
 practice of it from his youth, trying first only to use his
 wings as a tame goose will do, so by degrees learning to rise
 higher till he attain unto skill and confidence."

 So wrote Wilkins, Bishop of Chester...''

A significant find, but for now it made no sense. That lost sadness when it is too late even to be sad. Time to go to sleep. 12.26am. Long day ahead.