For some people, the roll of thunder in the distance is a welcome sound, a sign that rain is on the way and maybe a chance to sit and watch the storm roll in. For others, storms can be anxiety-inducing, creating fear of the wind and lightning and potential damage they can cause.

Thunderstorms are a force of nature, and one of the most powerful ones at that. Even the most mild storms produce potentially dangerous lightning and must be respected. Some storms are strong enough to produce storm warnings, with thunderstorm watches and warnings advising us to be weather aware and have plans to seek shelter and safety. 

The difference between storm watches and warnings can cause confusion, so knowing what each means is essential. A severe thunderstorm watch means conditions are favorable for a severe thunderstorm in the watch area and people in the watch area should be prepared to act, according to the National Weather Service. A severe thunderstorm warning means severe weather has been indicated on radar or confirmed by trained weather spotters. A severe thunderstorm warning means there is imminent danger to life and property and everyone in the warned area should take shelter indoors in a substantial building. 

No matter how strong the storm, the best place to be during a thunderstorm is inside, away from doors and windows, according to the National Weather Service. Always remember to heed the saying when thunder roars, go indoors. If you cannot get indoors, the next safest place is a hard-topped vehicle with all the windows rolled up. Thunder is the sound that lightning makes and can be heard from a distance of about 10 miles from a lightning strike. Once you hear thunder, you should always head indoors immediately. 

Read on to learn more about thunderstorms.

They are extremely common

Thunderstorms certainly aren't an everyday occurrence locally, but they are an everyday occurrence globally — by a multitude of thousands. Across the world, an estimated 16 million thunderstorms occur each year, according to the National Oceanic Atmospheric Administration. At any given moment, about 2,000 thunderstorms could be raging across the planet. 

In certain parts of the United States and the world, thunderstorms are much more common than in other places. Here in the United States, Florida leads the way on thunderstorms. Some parts of southern Florida experience 108 or more days a year with thunderstorms. Meanwhile, the coastal regions of California, Oregon and Washington experience only nine or fewer thunderstorm days a year, according to the National Weather Service. 

Where do you think northern Illinois falls on the spectrum? As much as it seems like hearing a rumble of thunder in the distance is a common occurrence, we generally experience between 36 and 45 days a year with thunderstorms, according to figures from the National Weather Service based on weather data from 1993 to 2018. That's only about 12% of the days of the year.

The place on Earth that experiences the most lightning strikes from thunderstorms is Lake Maracaibo in Venezuela, according to the United Kingdom's National Meteorological Library and Archive. The area experiences massive thunderstorms between 140 and 160 nights a year, and these storms can cause an average of 28 lightning strikes per minute for as long as 10 hours at a time. 

They all form in the same way

For a thunderstorm to form, certain atmospheric conditions are required. Along with moisture, thunderstorms require instability in the atmosphere and lift, which triggers motion in the atmosphere, according to the NOAA. The moisture often comes from the ocean, even in places far from a coast, thanks to strong winds. Instability can be created when warm, moist air near the ground is pushed upward into colder, drier air. As the air pushes upward, thunderclouds form.

A thunderstorm goes through a life cycle just like all living things do. Each storm has three stages: the developing stage, the mature stage and the dissipating stage. The developing stage is when the warm, moist air is being pushed aloft, creating an updraft and causing the towering thunderclouds we associate with these storms to form. During the developing stage, little if any rain falls, but there can be occasional lightning and thunder, the NOAA reports. The mature stage begins when heavy precipitation starts to fall, creating a downdraft. The mature stage is when a storm is at its most dangerous, able to produce heavy rain, hail, lightning, strong winds and even tornadoes. The final stage, the dissipating stage, occurs when the updraft is overcome by the downdraft. During this stage, a gust moves away from the storm, which limits the supply of warm, moist air that was powering the storm. During this stage, rain can continue, but with less intensity. Lightning can also continue to occur.

There are several different kinds

While all thunderstorms form in the same way, not all thunderstorms are equal. There are actually four different types of thunderstorms, according to the NOAA. The most simple of storms are single-cell thunderstorms, and these storms are usually small and weak, lasting only an hour or two at most. These are the storms we often experience on summer afternoons because they are created as the atmosphere warms during the day. They can produce heavy rain and lightning.

Multi-cell storms are another common type, and these often are preceded by a gusty front sweeping across an area. These storms can have a short lifespan but may last a few hours. They often produce heavy rains and can be accompanied by hail, strong winds, flooding and brief tornadoes, the NOAA reports. Squall lines are groups of storms arranged in a long line, sometimes even hundreds of miles long. They are usually accompanied by high winds and heavy rains, and they pass quickly because the systems are usually no more than 10 miles to 20 miles wide. 

Supercells are well-organized, long-lasting storm systems. These powerful storms feed off an updraft that is rotating, and thunderclouds can tower as high as 50,000 feet above the ground, according to the NOAA. Most large tornadoes are the result of supercell thunderstorms. Rotation in the thunderclouds can sometimes be detected by radar, possibly as early as an hour before the storm may spin off a tornado.  

They are more dangerous than people think

When we think about dangerous weather events, tornadoes and hurricanes would probably top the list for most people, but thunderstorms — specifically lightning — can be deadly. The number of lightning fatalities that occur in the United States varies from year to year, but from 2009 to 2018, the U.S. averaged 27 lightning-related deaths, according to the National Weather Service. 

Only about 10% of people who are struck by lightning are killed, and the remaining 90% can have varying levels of injuries and disabilities. The odds of being struck by lightning in the United States in any given year are about 1 in 1.22 million, and the odds of being struck by lightning in your lifetime (with an estimated life span of 80 years) are about 1 in 15,300, the weather service reports. For some perspective, consider that the odds of winning the Powerball jackpot are about 1 in 292.2 million. 

Being struck by lightning can cause cardiac arrest, the weather service reports. Some lightning strike victims can be resuscitated, but brain damage is also possible, and in some cases it may be irreversible. Always remember that no place outdoors is safe when thunderstorms are nearby. If you hear thunder, lightning is close enough to strike you, the weather service advises. When you hear thunder, move indoors or to a safe structure, such as an enclosed, metal-topped vehicle. If you are caught outside, move away from elevated areas and get out of any body of water. Stay away from objects that can conduct electricity, such as power lines or barbed wire fences, and never take shelter under a tree or by lying flat on the ground.

They occur on other planets too 

There's a lot we don't know about the other planets in our solar system, but we do know some of them experience storm systems at least somewhat similar to what we experience here on Earth. For example, Venus, our nearest planetary neighbor, experiences lightning, possibly even more lightning than Earth does, according to NASA. And a storm has been raging on Jupiter for more than 300 years, although the storm has been getting smaller for the past 150 years. 

Saturn experiences frequent storm activity, particularly in its southern hemisphere, and the planet's storms can last for years. Even Saturn's moons experience storms. Neptune also experiences massive storm systems, and they can last years at a time, NASA reports. Mars experiences intense dust storms, and they can sometimes affect the entire planet.