Rain is associated with water. During the summer season from time to time we ask God for rain. We need rain not only because it is hot and rain usually refreshes us but also because we know that crops depends much on rain. The more crops we get the better for us and for economy of the country we live in and for other countries as well. Plants, tress, animals, birds, and insects - they all need rain. Rain is necessary for their life.
Going back to the association of water and rain, water is the source of all life on Earth. It is the only known substance that can exist naturally as a gas, liquid, and solid within the relatively small range of air temperatures and pressures found on the surface of the Earth. The total amount of water present on the Earth is fixed and does not change. However, powered by the Sun, water is continually being circulated between the oceans, the atmosphere and the land. This circulation and conservation of the Earth's water, known as the water cycle, is crucial component of weather and climate. Climate dictates the amount of rainfall the soil receives and how much water is cycled back to the atmosphere through evaporation.
The need for accurate rainfall predictions is readily apparent when considering the many benefits such information would provide for river control, reservoir operations, forestry interests, flash flood watches, etc. Climate prediction centeris one of the services that provide information on rainfall predictions. It is one among several centers under the National Centers for Environmental Prediction (NCEP), part of the National Weather Service (NWS) in the National Oceanic and Atmospheric Administration (NOAA). The Center serves the public by assessing and forecasting the impacts of short-term climate variability, emphasizing enhanced risks of weather-related extreme events, for use in mitigating losses and maximizing economic gains.
While the data required to make rainfall predictions has been available for quite some time, the complex, ever-changing relationships among the data and its effect on the probability, much less the quantity, of rain has often proved difficult using conventional computer analysis. The use of a neural network, however, which learns rather than analyzes these complex relationships, has shown a great deal of promise in accomplishing the goal of predicting both the probability and quantity of rain in a local area to an accuracy of 85%.
Rainfall predictions associated with climate change may be variable across even one country, not speaking about larger areas on a global scale. For example across
Some areas used to and expecting to experience regular rainfall are predicted to suffer a significant reduction in regular rainfall. These areas are mainly in the south and east of