Forces of Nature

Do scientists really think a massive earthquake could break California in two?

Every night on the news, the weatherperson reports the UV index. What is the UV index and how is it calculated?

What causes the seasons? Why are the seasons reversed in the Northern and Southern Hemispheres? And if the Earth moves in an elliptical orbit around the Sun, why don't we have two summers and two winters every year?

By Sascha Bos

You may have heard that you can figure out how far away lightning is by how long it takes for the thunder to arrive after you see the flash. Is this true? How do you calculate it?

Why is it colder at the top of a mountain than it is at sea level? Heat rises, and the top of a mountain is closer to the sun, so shouldn't it be hotter at the top of a mountain?

By HowStuffWorks.com Contributors

Precipitation can vary from rain to snow when the temperature is below freezing. Why does precipitation not always fall as snow when it's below freezing?

We can usually see rainbows right after a rainstorm on a warm Spring day. These giant colorful arcs stand out against the dark rain clouds. Have you ever wondered what causes this phenomena? Find out how rainbows are created in this article from HowStuffWorks.

By Austin Henderson

There's often a strong, quite pleasant, smell right after a rain shower. What accounts for petrichor, the 'smell of rain'?

By Kathryn Whitbourne & Desiree Bowie

A tornado is one of those amazing, awesome acts of nature that simply leaves you dumbfounded -- a huge, swirling, 200-mph beast of a storm that appears to have a mind of its own.

By Marshall Brain, Robert Lamb & Yara Simón

How does the aurora borealis (the Northern Lights) work? What causes it? Why can you only see it in the North? Are the myths about it producing sound true?

By Austin Henderson

How often have you watched a weather forecaster point to a spiral-shaped cloudy mass with a sense of dread and fascination? What fuels these ferocious storms?

By Marshall Brain, Craig Freudenrich, Ph.D. & Robert Lamb

Lightning is an incredible force of nature. And like many natural phenomena, lightning is not always what it seems. Go behind the mystery and learn what's really going on when lightning strikes.

By John Zavisa & Jesslyn Shields

What happens when the rains cease and water levels dry up precipitously? Everything from abundant grasses to apex predators suffers the consequences.

By Robert Lamb

Inject heat, ash and fire into a spinning mass of air. Watch as a funnel of flames leaps from the ground, reaches for the heavens and then races forward to consume everything in its path. Is such a phenomenon possible?

By William Harris

Human activities (such as leaving a campfire unattended, discarding lit cigarettes, debris burning and intentional arson) are among the top causes of wildfires.

By Jessika Toothman & Yara Simón

At some point in your life, a coach may have enthusiastically told you to "fight fire with fire." Coach, of course, was speaking metaphorically. Do firefighters actually employ this strategy?

By Robert Lamb

Without question, nature can produce beautiful light shows. Add wind, rain and hail, and you have an awe-inspiring event. But thunderstorms are not to be taken lightly. Here's how to stay safe as Mother Nature displays her strength.

By Sara Elliott

Who likes getting caught in a downpour without an umbrella? Not this guy and not us. Are we ever going to achieve rainmaker status so we can dial up a few gentle showers one day and a blast of sunshine the next?

By William Harris

Though they're outranked by other, more dangerous natural phenomena, dust storms can still do serious damage to life and property. What causes these massive storms?

By Vicki M. Giuggio

Tornado chasers generally stay about a mile away from the tornado itself -- but not IMAX cinematographer Sean Casey. He has built a Tornado Intercept Vehicle and hopes to withstand a direct hit. Check it out.

By Tracy V. Wilson

Learn how avalanches form, how long you can stay alive while buried under an avalanche and what steps you can take to survive.

By Tracy V. Wilson

The wall of water that struck northern Japan on March 11 claimed more than nearly 16,000 lives. While the human and cultural extents of this natural disaster are difficult to grasp, we can explain the physical properties that led to it.

By Robert Valdes, Nathan Halabrin & Robert Lamb

Acid rain is caused by emissions of sulfur dioxide and nitrogen oxides from power plants, cars and factories. Find out how acid rain is produced, how it affects natural and man-made objects and how governments aim to reduce it.

By Sarah Dowdey

There are obvious craters on Earth (and the moon) that are evidence of a long history of massive objects hitting planet Earth. But what would happen if an asteroid hit Earth today?

By Marshall Brain & Sarah Gleim

San Francisco has a new airport that's supposed to stand up to the rigors of an earthquake. Does that mean that planes can land while a massive quake is shaking the city?

By Katherine Neer