Weather is a word used to describe the state of the atmosphere. For eg, weather could be used to describe whether the day would be cold or hot, stormy or calm, wet or dry, clear or cloudy. It also helps to define the degree of such conditions as well. Most of the weather phenomenon occur in the lowest of the layer of the atmosphere called the troposphere. Troposphere is just below the stratosphere. Another definition of weather is that it refers to the day to day precipitation activity and temperature whereas in contrast climate refers to the same atmospheric conditions over a longer interval of time. If nothing is mentioned alongside weather, it is assumed that it is referred to the weather of the "Earth".
Weather is driven by temperature, air pressure and moisture differences between one place and another. The reason for these differences to occur might be the different angle of the sun at any particular spot, which varies with latitude. The largest scale atmospheric conditions are caused due to the strong temperature contrast between polar and tropical air. Some examples of such conditions are the Ferrel Cell, the Hadley Cell, the Jet Stream and the Polar Cell. Extratropical cyclones, which exist in the mid latitudes, are caused by instabilities of the jet stream flow.
In this sub category you can download free PNG images: Weather Nature. In this category "Weather" we have 22 free PNG images with transparent background.