Weather forms primarily from conditions in the local atmosphere that change frequently over short periods of time. Weather, in the broadest sense, is the condition of the atmosphere in a set location that varies on a daily, weekly, or monthly basis. Weather is created by several different factors, such as temperature of the surrounding land and air, levels of humidity and type and volume of precipitation.
In addition to those factors, weather is created by air pressure, and is influenced by the amount and type of cloud cover, as well as the direction, frequency and force of winds. Geographical location, the seasons, and altitude also affect weather patterns that form on a short-term and long-term basis. Weather generally refers to the atmospheric conditions that exist in the troposphere, which is the level of the atmosphere closest to the Earth. Cloud cover rarely extends beyond the uppermost layer of the troposphere, and most precipitation forms in that area as well. Some factors that create weather, such as jet streams and high air waves, form in the upper regions of the troposphere and affect levels of pressure in the atmosphere below. These factors contribute to daily changes in weather patterns and control seasonal weather patterns as well.