People generally use the terms weather and climate for the same phenomenon, without realizing the differences between the two. The weather at a place is defined by measuring certain atmospheric parameters such as temperature, pressure, humidity, wind strength and direction, rainfall, snowfall, cloud, sunshine, etc, at a particular time. Depending on the values of these parameters, the weather of a place may be hot or cold, dry or humid, clear or cloudy, rainy, and so on. There are various ways of defining the state of the weather at a place, at a particular time. Weather forecasts are normally for a specific place, and are valid for a specific period of time. For example, the weather forecast for up to 2–3 days is known as a short-range forecast; that for a period of 3–10 days is known as a medium-range weather forecast, and that for a month or season is known as a long-range or extendedrange weather forecast. These forecasts provide the state of the atmosphere during the stated number of days, in terms of the temperature, surface pressure, humidity, rainfall, snowfall, clouds, sunshine, fog, frost, thunder, gale, and so on. These forecasts also state the possibility of severe weather conditions, such as cyclones, tornadoes, thunderstorms, floods, droughts, avalanches, and so on. Every country has its own operational weather agency, which regularly monitors the state of the atmosphere at different weather observatories.