Daily Postcard: Bolts of lightning crackle in the sky during the rainstorm Thursday night above Overlook Park in White Rock. It takes about 5 seconds for the sound of thunder to travel a mile. So, when you count the number of seconds between seeing a crack of lightning and hearing the thunder, divide that number by 5 and that is how many miles away the lightning was when it struck. Source: nationalgeographic.com. Photo by Sarah Jimenez