Lightening strikes from the ground up...but we see it reversed?

Lightening strikes from the ground up…that’s what a physics professor said. At the time it made perfect sense, but it’s been a few years and I’m forgetting the basics. I know quite a bit about physics, but it’s mostly in the field of astronomy. This is probably a question that could be easily answered with a few searches on the net, but I figured you guys would like to show your intelligence with it. Anyway, enough dribble…If lightening strikes from the ground up, why do our eyes see it as a top-down effect?

It’s true . . . Once I was in Rocky Mountain National Park, up on top of a rocky promontory overlooking a valley. I saw lightning suddenly strike only a few hundred feet in front of me. The closest I’ve ever been to a lightning strike.

Indeed I saw it flash up from the ground. Right near the ground its color was purple and pink.

As for why it seems to strike downward, I don’t know. It’s an optical illusion, and it moves awfully fast . . . you don’t see it on the ground in front of you, but you do see the cloud, so your brain is fooled into thinking you see it move down from the cloud.

Clouds are negatively charged compared to the ground. The bolt travels from negative to positive, or from the cloud down. But the ground (or whatever is going to be struck) ionizes a path up to meet the bolt, so lightening DOES go up. The connection is made a few feet off the ground and the current transfers. I think the term for the upward bolt is ‘leader’.

Or maybe not.

Does lightning go from ground to cloud or vice versa?

It’s a question a lot of people like to answer. (There are several links and several “free hand” explanations in the above thread.)

The step leaders are formed as the charge in the cloud gets larger. They are ionized pathways in the air. As the step leaders grow toward the ground, positive streamers start to form on edges and corners of stuff on the ground and wait patiently for the step leaders to reach them. At that time, there is a low resistance path of ionized air between the cloud and the earth and a few zillions volts discharge. The air around the discharge path explodes and we see the flash of heat about the temperature of the sun.

The normal lightning stikes from the cloud to the ground. Large objects on the ground can generate a lightning strike from the ground to the cloud and of course there is cloud to cloud lightning.

Check How Lightning Works at for a nice discusion of what happens.


While the links provided head to detailed information on the phenomenon of lightning, and as such are helpful, the OP accepted the physics professor’s word on authority (apparently) but wanted to know why we see it as top-down.

So I’ll add to ishmintingas’ speculations … you also might see lightning between the clouds and assume that it is ‘stored up’ up there and occasionally is cast down to the earth (especially if you’re an ancient Greek).

panama jack

lightning’s striking again…

I watched a PBS special on lightning once and gave the tech reasons, with diagrams, about how it strikes up but when they show it in slow motion (live footage) several times it still looked like it came DOWN. I’m not convinced. This sounds like one of those ‘bumblebees-can’t-fly-according-to-physics’ things.