Why does it lightning without thunder

A "stepped leader" of negative charge descends from the cloud seeking out a path toward the ground. Although this phase of a lightning strike is too rapid for human eyes, this slow-motion video shows it happening.

As the negative charge gets close to the ground, a positive charge, called a streamer, reaches up to meet the negative charge. The channels connect and we see the lightning stroke. We may see several strokes using the same path, giving the lightning bolt a flickering appearance, before the electrical discharge is complete. That's five times hotter than the surface of the Sun! The heated air expands explosively, creating a shockwave as the surrounding air is rapidly compressed.

The air then contracts rapidly as it cools. If we are watching the sky, we see the lightning before we hear the thunder.

That is because light travels much faster than sound waves. Typically, a cloud-to-ground flash lowers a path of invisible negative electricity towards the ground. Objects on the ground generally have a positive charge, and because opposites attract, an object about to be struck sends out an upward streamer.

When these two, oppositely-charged paths meet, they send a return stroke zipping back up to the sky. It is this return stroke that produces the visible flash. Silent lightning has swept across with UK. So what is it and why can't you hear the thunder? A lightning strike is when an electric discharge from the atmosphere is sent down into an earth-bound object. Thunder is the sound caused by the lightning and depending on the distance, the sound can be a short violent crack or a slow, low grumble.

The phenomenon that is called silent or heat lightning is simply cloud-to-ground lightning that occurs very far away, with thunder that dissipates before it reaches the observer and cannot be heard. Non-stop lightning goes by a number of different names, including silent lightning, summer lightning, dry lightning and heat lightning. It is most often called heat lightning as the phenomenon regularly occurs during the summer months.

Non-stop lighting is believed by some to be generated from hot and humid conditions alone, but this is false. You can only hear thunder within 10 miles of a storm, but a flash of lightning can be seen up to miles away from bigger disturbances.

Mountains, hills, trees, buildings and even the curvature of the Earth can make it difficult to see the storm itself. Any higher-level clouds which are around can also help to reflect the light, meaning you can still see a faint flash off the horizon.

While a number of people incorrectly think heat lightning is a specific type of electric strike, it is simply the light produced from a distant thunderstorm. Landmasses, such as continents and other large areas of land surrounded by sea, experience more storms than the oceans. Thunderstorms are much more frequent in the tropical areas than the higher latitudes of the Earth.