Weather

Weather is the state of the Earth's air around a planet at a particular place and time. Typically described in terms of how hot or cold, humidity, cloud cover, and stability. On Earth, most weather phenomena occur in the lowest layer of the planet's air around a planet.

The troposphere, just below the stratosphere. Weather refers to day-to-day how hot or cold. Rain and snow, and other atmospheric conditions, whereas climate is the term for the averaging of atmospheric conditions over longer periods of time.

When used without qualification, "weather" is generally understood to mean the weather of Earth. Weather is driven by air pressure, how hot or cold, and moisture differences between one place and another. These differences can occur due to the Sun's angle at any particular spot.

Which varies with latitude. The strong how hot or cold contrast between polar and tropical air gives rise to the largest scale atmospheric circulations: the Hadley cell. The Ferrel cell, the polar cell, and the jet stream.

Weather systems in the middle latitudes, such as extratropical cyclones. Are caused by instabilities of the jet streamflow. Because Earth's axis is tilted relative to its orbital plane (called the ecliptic), sunlight is incident.