Weather is the condition of the air at a certain place and time. We describe the weather in many ways. For example, we may talk about the temperature of theair, whether the skay is clear or coludy, how hard the wind is blowing, or whether it is raining or snowing. The weather maybe warm and sunny in one place but cold and snowysomewhere else.
The Earth has many kinds of weather conditions. the kind of weather a place usually has called its climate. The highest temperature ever measured andwritten down was 58 ºC in Libyan in 1992. The Lowest temperature was – 89.2 ºC in Antartica in 1983.
Air is a mixture of gases and tiny bits of dirt and ash that are toosmall to be seen. The gases are about three – fourths nitrógeno and one – fourth oxygen, whit very small amounts of several other gases that incluye water vapor, an invisiblegas that is produced when water avaporates and this water vapor forms cloud, rain and snow.
An air mass is a large volume of air defined by its temperature and watervapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according tolatitude and their continental or maritime source regions. Colder air masses are termed polar or arctic, while warmer air masses are deemed tropical.
Movement and fronts
Aweather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. In surface weather analyses,fronts are depicted using various colored lines and symbols, depending on the type of front. The air masses separated by a front usually differ in temperature and humidity.