World climate is the average (statistically, mean and variability) weather, usually over a 30-year interval. It is measured by assessing the patterns of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. Climate is different from weather, in that weather only describes the short-term conditions of these variables in a given region. The global sub seasonal and seasonal forecast maps we provide are basedon departures from the long term averages that define world climate.
A region's climate is generated by the climate system, which has five components: atmosphere, hydrosphere, cryoshere, lithosphere and biosphere.
The climate of a location is affected by its latitude, terrain and altitude, as well as nearby water bodies and their currents. Climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was originally developed by Wladimir Koppen. The Thornthwaite system in use since 1948, incorporates evapotranspiration along with temperature and precipitation information and is used in studying biological diversity and the potential effects on it of climate changes. The Bergeron and Spatial Synoptic Classification Systems focus on the origin of air masses that define the climate of a region.
Global variables such as extreme precipitation and temperature and anomalies globally in precipitation and temperature and sea surface temperature changes that are forecast for coming months can be very powerful tools for decision makers across all sectors. New global variables are added from time to time. These maps are also updated every ten days to provide the latest information.