Weather is the state of the atmosphere at a specific time and place, with respect to temperature, precipitation, and other factors such as cloudiness. Weather is generated by many forces, some obvious, some not. Warm, humid air masses blowing in from oceans, for example, fuel rains. Sunlight heats the land, generating thermals that help produce summer thunderstorms.
Mountains and cities also affect the weather. In mountains this occurs because the wind must rise as it crosses over the ridge. This lifts the air, causing it to cool. That produces clouds, rain, or snow.
Cities, on the other hand, produce urban "heat islands" where roads, parking lots, and rooftops warm in the sun. This not only raises the city's temperature, but it can affect the weather, producing thunderstorms in some cities or altering storm tracks in others.
Predicting the Weather
Weather forecasting is the art of predicting what will happen in the future. In its simplest form, it's merely a matter of looking out the window to see what types of clouds are around and which way they are moving. Knowledge of local weather patterns can then allow fairly good predictions for the next 12 to 24 hours.
Professional forecasters have a wide variety of other tools. Weather stations scattered around the globe allow them to make detailed weather maps, as do satellites, which allow forecasters to see what is happening far out to sea, where there are no weather stations. Weather balloons and radar also contribute.
Nevertheless, long-run weather forecasting is notoriously difficult. That's because weather prediction involves a mathematical concept called chaos theory, in which extremely small errors in measuring today's weather conditions can snowball into large, seemingly random, errors in long-range forecasts.
It has been said, for example, that a butterfly flapping its wings today in China could produce (or prevent) tornadoes two weeks from now in Kansas. While this so-called butterfly effect is undoubtedly overstated, the basic concept is simple: Even the most minor factors can alter long-term weather forecasts.
Most weather forecasters believe that accurate forecasting more than two weeks into the future will always be impossible. Today, anything beyond five to seven days involves substantial guesswork and is often wrong.
Related Topics
You May Also Like
Go Further
Animals
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them? - This biologist and her rescue dog help protect bears in the AndesThis biologist and her rescue dog help protect bears in the Andes
- An octopus invited this writer into her tank—and her secret worldAn octopus invited this writer into her tank—and her secret world
- Peace-loving bonobos are more aggressive than we thoughtPeace-loving bonobos are more aggressive than we thought
Environment
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
- Food systems: supporting the triangle of food security, Video Story
- Paid Content
Food systems: supporting the triangle of food security - Will we ever solve the mystery of the Mima mounds?Will we ever solve the mystery of the Mima mounds?
- Are synthetic diamonds really better for the planet?Are synthetic diamonds really better for the planet?
- This year's cherry blossom peak bloom was a warning signThis year's cherry blossom peak bloom was a warning sign
History & Culture
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
- How technology is revealing secrets in these ancient scrollsHow technology is revealing secrets in these ancient scrolls
- Pilgrimages aren’t just spiritual anymore. They’re a workout.Pilgrimages aren’t just spiritual anymore. They’re a workout.
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- This ancient cure was just revived in a lab. Does it work?This ancient cure was just revived in a lab. Does it work?
- See how ancient Indigenous artists left their markSee how ancient Indigenous artists left their mark
Science
- This 80-foot-long sea monster was the killer whale of its timeThis 80-foot-long sea monster was the killer whale of its time
- Every 80 years, this star appears in the sky—and it’s almost timeEvery 80 years, this star appears in the sky—and it’s almost time
- How do you create your own ‘Blue Zone’? Here are 6 tipsHow do you create your own ‘Blue Zone’? Here are 6 tips
- Why outdoor adventure is important for women as they ageWhy outdoor adventure is important for women as they age
Travel
- Slow-roasted meats and fluffy dumplings in the Czech capitalSlow-roasted meats and fluffy dumplings in the Czech capital
- Want to travel like a local? Sleep in a Mongolian yurt or an Amish farmhouseWant to travel like a local? Sleep in a Mongolian yurt or an Amish farmhouse
- Sharing culinary traditions in the orchard-filled highlands of JordanSharing culinary traditions in the orchard-filled highlands of Jordan