Ambipolar Field Reel

Narration: Glyn Collinson

Transcript:

It’s called the ambipolar field and it’s an agent of chaos.

It’s an electrical field. It begins at about 250 km above your head and it keeps going.

The atmosphere up there is different than the atmosphere down here. Thinner, right? There’s less of it.

So, think about just one atom – here it is – the Sun shines on it and it breaks off this electron. So, now we have this negatively charged electron and this positively charged ion, and the two are attracted towards each other.

The electron would happily escape all by itself, but the ion still feels the big tug of gravity. So, as the electron tries to pull away, the electric force forms between the two to restrain it to keep it from escaping. And it also helps pull the ion upwards.

The field works in both directions, it is ambipolar. Imagine you’re walking a dog and you’ve got a tiny tiny little dog and it’s pulling on a leash. That dog is going nowhere.

This ion and electron pair that you’ve been thinking about, they are only one in an enormous sea of the ionosphere.

But, overall, because gravity is pulling down on the ions, it adds up. And over a large distance, you get this field forming.

It’s like this conveyor belt that’s countering gravity and lifting the ions up so they can escape to space. Which is why it may have had an impact on the evolution of the atmosphere.