How old is someone right now that was born on leap year 8 years ago?

If he was born 8 years ago, then he is 8 years old now.

If he was born on February 29th, then most years
won't have the date of his birth in them.  Too bad.

Jet streams are relatively narrow bands of strong wind in the upper levels of the atmosphere. the winds blow from west to east in jet streams but the flow often shifts to the north and south. jet streams follow the boundaries between hot and cold air. the earth's rotation is responsible for the jet stream as well.

2. they have negligible mass.