school energy&environment

The weather forecasts

The capacity of making weather forecasts has always been one of Man’s requirements, in order to be able to manage and plan all his activities, from his leisure time to sports, to agricultural activities and industrial activities in the open air.
Nowadays our knowledge about the weather and meteorological phenomena has greatly improved, even though we are far from totally comprehending them, and consequently, weather forecasts are increasingly reliable. In Italy the official body in charge of formulating the weather forecasts is Servizio Meteorologico dell’Aeronautica Militare, the Meteorology Service of the Military Aeronautic Service, in collaboration with the European and World Meteorological Organization.
The Meteorology service publishes the official Meteorology Bulletin daily, making use of the data collected in the stations on ground (positioned in all the airports and integrated by other stations scattered around the national territory). Some of these are equipped with instruments for radar monitoring and for launching probe balloons. The data are then integrated with the recordings carried out by the world network of meteorology satellites, in particular by the European METEOSAT satellites.
For short term forecasts, with indications that are valid up to 12-24 hours, ground level and high altitude synoptic weather charts are used. For this type of forecasts, the experience and personal capacity of the meteorologist are still fundamental. Therefore these are very subjective forecasts, and their reliability depends greatly on the meteorologist’s ability. For mid-term forecasts, valid up to a maximum of 3-5 days, mathematical-numerical methods are prevalently used. In this case the forecasts are based on a mathematical model of the atmosphere, that represents a state of the weather with a series of equations in which the unknown values are the temperature, pressure, air density and wind-speed. These methods require the use of very powerful and rapid calculators because simulation requires an enormous number of calculations. The evolution of high power computers for civil purposes has taken place, as a result of the research to satisfy the need to carry out calculations in the meteorological field.
For long term forecasts, that are valid from a week to a month, instead, statistical analyses are used, based on series of meteorological data over a period of time. In practice the mean conditions of the weather in the past are studied in order to foresee the possible behaviour of the weather in analogous meteorological conditions. This type of study is more suited to study the climate than to solve the problems of weather forecasts.