Question

what would happen if the earth's axis was vertical

Answer 1

The main reason why we have seasons during the year is because the Earth is tilted 23.5 degrees on its axis. In it's orbit around the sun, when the Earth is tilted toward the sun it is summer in the Northern Hemisphere and when the Earth is tilted away from the sun it is winter in the Northern Hemisphere. In the Southern Hemisphere it would be the other way round. Since the Earth orbits the sun steadily, this pattern repeats itself every year.

Answer 2

Yes...when the Earth is tilted toward the sun it is summer in the Northern Hemisphere and when the Earth is tilted away from the sun it is winter in the Northern Hemisphere. In the Southern Hemisphere it would be the other way round...that's why it repeats again