Weather: What It Is and Why We Have It

An Explanation of Weather and Why We Have It

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Weather is the state, or condition, of the atmosphere at any time.

It is popularly thought of in terms of temperature, precipitation (if any), cloud cover, and wind speed. Because of this, words like hot, cloudy, sunny, rainy, windy, and cold, are often used to describe it. 

Weather is caused by uneven heating of Earth's surface.

Energy from the sun heats Earth's surface. But because our planet is a sphere, this energy isn't absorbed equally everywhere on Earth.

 

Regardless of season, the sun's rays always strike most directly near the equator, which keeps temperatures there higher than anywhere else on Earth. At latitudes farther from the equator, sunlight strikes the surface at lower angles -- that is, the same amount of solar energy that strikes near the equator strikes here too, but is spread over a much greater surface area. As a result, these locations are heated less intensely than those near the equator. It is this temperature difference that drives air to move around the globe, giving us weather.

So you can think of weather as the atmosphere's way of moving heat from one part of the world to another in an attempt to balance it out. However, because of how the Earth heats up (as we've just learned above), the atmosphere's work is never done -- which is why we're never without weather.

More: What if weather didn't exist?

How Weather Differs From Climate

Unlike climate, weather has to do with short-term (on the scale of hours to days ahead) variations of the atmosphere's behavior, as well as how these affect life and human activities "in the now." To learn more about weather in relation to climate, read About Weather's Weather vs. Climate - What's the Difference?

Where to Check the Weather

Where you get your weather forecast is a matter of personal taste in design, how much information you want, and how much you trust a forecast. Here are the top 5 most popular weather sites we recommend:

  • The NOAA National Weather Service offers quality forecasts without added fluff or ads. Also good if you're interested in a national overview of what's happening with the weather.
  • The Weather Channel is one of the largest names in commercial weather and is a popular choice if you prefer your weather alongside your news headlines.
  • Weather Underground uses its network of over 140,000 personal weather stations to give you the weather closest to your neighborhood (not that at your closest major airport).
  • AccuWeather is a leader in online weather forecasting. As its name suggests, it prides itself on accurate forecasts.
  • Unisys Weather. Unisys is an IT company that provides weather data services with an emphasis on weather plots, maps, and images.