A thunderstorm is a powerful rainstorm that brings lightning and the rumbling sound of thunder. These storms are sometimes called electrical storms because lightning is a giant spark of electricity in the sky. A thunderstorm is a relatively short event, often lasting for only 30 to 60 minutes. Understanding how these events happen and how to stay safe makes them less scary and more fascinating.
The Ingredients That Make a Storm
For a thunderstorm to form, the atmosphere needs three things: moisture, unstable air, and lift. Moisture provides the water vapor needed to make the clouds and the rain. Unstable air is warm and moist air that allows it to rise rapidly.
This warm, moist air rises into the cooler parts of the atmosphere. As it rises, the moisture cools and condenses to form a cloud. This rising column of air is called an updraft, and it builds a massive, towering cloud known as a cumulonimbus cloud. When the cloud gets heavy with water droplets and ice, the weight causes rain or hail to fall, which creates a downward column of air called a downdraft.
The Science of Lightning
Lightning is a massive, natural shock of static electricity, similar to what you might feel after shuffling your feet across a carpet. Inside the towering storm cloud, tiny ice crystals and water droplets move rapidly. As these particles bump against each other, they create a separation of electrical charges.
The lighter, positive charges gather at the top of the cloud, while the heavier, negative charges build up at the bottom. The negative charge at the cloud’s base is strongly drawn toward the positive charge on the ground below. When the difference in charge becomes too great, the air can no longer act as an insulator, and the electricity jumps through the air. This sudden rush of electricity is the brilliant flash we know as lightning.
The Science of Thunder
Thunder is the sound that lightning makes, happening because the air around the lightning bolt is heated to an extreme temperature. The electrical current of lightning can heat the air along its path to 50,000 degrees Fahrenheit, which is five times hotter than the surface of the sun. This intense heat causes the air to expand incredibly fast, like an explosion.
This rapid expansion creates a powerful shock wave that travels outward, which we hear as thunder. Even though the lightning flash and the thunder sound happen at the same moment, you always see the light before you hear the sound. This is because light travels much faster than sound. If you count the seconds between the flash and the sound, every five seconds equals about one mile of distance between you and the lightning.
Simple Storm Safety Rules
If you hear thunder, lightning is close enough to strike you, so you must immediately go inside a sturdy building or a car. Once indoors, stay away from windows and doors, as they can allow the lightning’s energy to travel inside.
You should also avoid taking a bath, shower, or washing dishes, because lightning can travel through the plumbing’s metal pipes and water. Wait at least 30 minutes after the last sound of thunder before you go back outside to ensure the storm has completely passed.