The lightning and thunder sound occur at the same time, but an observer will experience a delay in hearing the thunder depending on the distance from the lightning strike.
Light travels at slightly less than 3.00 x 106 kilometres/second or around 1.88 x 106 miles/second. That is fast. This means that we see the lightning virtually immediately.
However, under some conditions sound travels at a measly ~1/3 kilometre/second (or ~1/5 mile/second).
First, we must know that sound travels at different speeds, depending on the humidity,
altitude, and temperature. To simplify, let us assume dry air at sea level at 68° F.
------- Kilometers ------- Miles
Speed: 1235 km/hr, 767 mi/hr
Speed: 20.58333 km/min, 12.78333 mi/min
Speed: 0.343056 km/sec, 0.213056 mi/sec
By time: ~1/3 km/sec, ~1/5 mi/sec
x 3 sec: 1.029167 km/(3 sec)
x 5 sec: 1.065278 mi/(3 sec)
By distance: ~1 km/(3 sec), ~1 mi/(5 sec)
What does this mean? When you see the lightning start counting seconds and you then know how far away is the lightning.
If it is almost simultaneous, youch, the lightning struck very close. However,
if the time between the flash and the thunder is 3 seconds, then the lightning is about 1 kilometre away; or
if the time between the flash and the thunder is 5 seconds, then the lightning is about 1 mile away.
How do I count seconds? Anyway you like - 1 little second, 2 little seconds, 3 little seconds;
1 Murrumbidgee, 2 Murrumbidgee, 3 Murrumbidgee etc; or 1 Mississippi, 2 Mississippi, 3 Mississippi...
If you get to 6 stop worrying.
Lightning does have sound. Depending upon the distance of the lighting bolt, it may be audible instantaneously or it may take several seconds for the sound waves to reach your ears. The further away the lighting, the longer it will take for the thunder to follow.
Just for fun: If you see a clap of thunder, call a journalist! More seriously, if you see a flash of lightning and hear a clap of thunder at almost the same exact time, it means that the electrical discharge that generated both the lightning and the thunder is very close to you, and you should take precautions immediately to avoid injury to yourself. Usually, the most practical precaution is to seek shelter in a building protected by lightning rods or a metal vehicle that will conduct electricity around you more readily than through you!
Since light travels faster than sound, you can tell how many miles away a thunder storm is by counting. Lightning strikes. 5 seconds pass and you heard thunder. The thunder storm is 5 miles away.
Rain typically follows thunder within a few minutes, though the exact timing can vary. Thunder is produced by lightning, which can strike several miles away from the rain itself. Generally, if you hear thunder, you can expect rain to start shortly after, but it may take up to 30 minutes or more in some cases, depending on the storm's intensity and distance. For a rough estimate, counting the seconds between seeing lightning and hearing thunder, with every five seconds indicating approximately one mile, can help gauge how far away the storm is.
The speed of light is much faster than the speed of sound. You see the lightening before you hear the thunder.
The time it takes to hear thunder after lightning strikes is typically about 5 seconds for every mile of distance between you and the lightning.
Lightning does have sound. Depending upon the distance of the lighting bolt, it may be audible instantaneously or it may take several seconds for the sound waves to reach your ears. The further away the lighting, the longer it will take for the thunder to follow.
Thunder is our name for the sound made by lightning. The reason there is (usually) a delay between when you see the bolt of lightning and hear the thunder is that light travels more quickly than does sound. This is the reason that you can count seconds between seeing lightning and hearing thunder to figure out how close the lightning is to you. When the lightning is closer to you, the sound doesn't take as much time to travel to your ears and thus the gap between the lightning and thunder is shorter. So you can't see thunder because it's merely a sound - but you can see the source of that sound.
P waves are also faster than S waves, and this fact is what allows us to tell where an earthquake was. To understand how this works, let's compare P and S waves to lightning and thunder. Light travels faster than sound, so during a thunderstorm you will first see the lightning and then you will hear the thunder. If you are close to the lightning, the thunder will boom right after the lightning, but if you are far away from the lightning, you can count several seconds before you hear the thunder. The further you are from the storm, the longer it will take between the lightning and the thunder. P waves are like the lightning, and S waves are like the thunder. The P waves travel faster and shake the ground where you are first. Then the S waves follow and shake the ground also. If you are close to the earthquake, the P and S wave will come one right after the other, but if you are far away, there will be more time between the two.
Very close to 5 seconds.
Thunder is what you hear, lightning is what you see, but both are due to electrical discharge in the atmosphere. They can seem to be separated in time to an observer (you see the lightening before you hear the thunder) because of the large difference in the speed of sound and the speed of light. If you are significant distance away (a few miles or kilometers), the light from the discharge will reach you almost instantly, but the sound can take several seconds to arrive. In fact you can measure the distance from you to the lightening in this way: for each second delay between seeing it and hearing it, the lightening bolt is approximately 300 meters, or 1000 ft away. Thunder is merely the rumbling sound that lightning creates. You hear the thunder after you see the lighting because light travels faster than sound. Lightning is the light that is emitted, and thunder is the sound.
If the lightening hit you, then you'd experience both at the same time. However, in general, you'll see lightening first, since that travels at the speed of light, and thunder second, as that travels at the speed of sound. One way to see this easily in practice is to go to a baseball game or cricket game and sit far away from the action - you will be able to see the batter hit the ball before you hear the sound of the ball hitting his bat.
Just for fun: If you see a clap of thunder, call a journalist! More seriously, if you see a flash of lightning and hear a clap of thunder at almost the same exact time, it means that the electrical discharge that generated both the lightning and the thunder is very close to you, and you should take precautions immediately to avoid injury to yourself. Usually, the most practical precaution is to seek shelter in a building protected by lightning rods or a metal vehicle that will conduct electricity around you more readily than through you!
Since light travels faster than sound, you can tell how many miles away a thunder storm is by counting. Lightning strikes. 5 seconds pass and you heard thunder. The thunder storm is 5 miles away.
The radio waves from a lightning stroke travel at the speed of light, you can hear them as clicks on a long-wave radio, and they travel round the world in 1/7th of a second.
This is because light travels faster than sound. Light travels so quickly that when a bolt of lightning occurs, you see it immediately. Sound moves at a few hundred miles per hour, meaning that it will usually take a few seconds for the thunder to reach you unless the lighting bolt was very close.
Thunder is sound waves. Sound waves hit us all of the time. If you mean lightning, then you would be toast... literally! thunder is the sonic boom produced by lighting so depending on how close you are to the lightning strike if you're close enough it can lead to temporary deafness or worse.