Why does the sky look green during some hail storms?
Scientists don't agree on why the sky may appear green during severe weather, although there is plenty of anecdotal evidence that it can mean hail may be nearby. One theory is that large amounts of water and ice in the updrafts of a severe thunderstorm will scatter green light, making the clouds appear green.
Does a hailstorm mean there could also be a tornado?
Not always, but possibly. Since large hail often appears near the area within a thunderstorm where tornadoes are most likely to form, you should assume a tornado could be nearby and seek appropriate shelter.
Yes. On April 4, 1977, a Southern Airways DC-9 crashed in New Hope, Georgia. Both engines of the plane ingested hail and lost thrust. The plane crashed onto the road and burst into flames. Two of the four crew members and 60 of the 81 passengers were killed; eight others on the ground were also killed.
In recent years, there have been numerous incidents of commercial airliners being forced to land after encountering hail during flight and causing severe damage to the aircraft, including crushing the nose cone and damaging the cockpit windscreen to such an extent pilots could no longer see through the screen.