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Lightning Distance Formula:
Where:
- \( d \) = distance in kilometers
- \( t \) = time between flash and thunder in seconds
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The lightning distance calculation estimates how far away a lightning strike occurred by measuring the time between seeing the lightning flash and hearing the thunder. Since light travels much faster than sound, this time difference can be used to calculate distance.
The calculator uses the simple formula:
Where:
Explanation: Sound travels approximately 1 km in 3 seconds (or 1 mile in 5 seconds). The formula divides the time difference by 3 to get the distance in kilometers.
Details: Knowing how far away lightning is helps assess danger. If the time between flash and thunder is decreasing, the storm is approaching. Lightning can strike up to 16 km away from a storm.
Tips: When you see lightning, start counting seconds until you hear thunder. Enter this time in seconds. For multiple strikes, use the closest one (shortest time) to determine the most dangerous part of the storm.
Q1: Why divide by 3?
A: Sound travels about 343 m/s (varies with temperature). Dividing by 3 approximates the km distance (343 m/s × 3 ≈ 1 km).
Q2: What if I count 30 seconds?
A: 30/3 = 10 km away. This is still potentially dangerous as lightning can strike from this distance.
Q3: When should I seek shelter?
A: The "30-30 rule": If time is ≤30 seconds (≤10 km), seek shelter. Wait 30 minutes after last thunder before resuming activities.
Q4: Does elevation affect the calculation?
A: Slightly, as sound travels faster in warmer air. At high elevations, sound may travel slightly faster.
Q5: Can I use this for other sound sources?
A: The principle works for any visible event with audible sound, but the exact conversion factor may differ.