The FAO Environment, Climate Change and Bioenergy Division (NRC) manages this website which provides four sets of real-time data:

• meteorological data from an automatic weather station;
• view over the Palatine Hill;
• images from Meteorological satellites;
• weather forecasts for various areas of the world.

For further information and comments please contact FAO-Climate@fao.org

i    Meteorological data

An automatic weather station has been installed on the roof of Building "F". The coordinates of the station are: Longitude East 12°29'; Latitude North 41°53'; Altitude 30 meters above sea level. Measurements are taken every 5 minutes. The measurements, and two derived indices, are the following:

• TEMPERATURE (in degrees Celsius °C), average value for the last fifteen minutes, maximum and minimum value for the day;
• HEAT INDEX (in degrees Celsius °C), average value for the last fifteen minutes, maximum and minimum value for the day;
  The "heat index" is an index that combines air temperature and relative humidity in an attempt to determine the human-perceived equivalent temperature - how hot it feels. The human body normally cools itself by perspiration which evaporates and carries heat away from the body. However, when the relative humidity is high, the evaporation rate is reduced, so heat is removed from the body at a lower rate, causing it to retain more heat than it would in dry air.
• WIND CHILL (unitless), average value for the last fifteen minutes, maximum and minimum value for the day;
  The human body loses heat largely by conduction and convection.[1] The rate of heat loss by a surface depends on the wind speed above that surface: the faster the wind speed, the more readily the surface cools. For inanimate objects, the effect of wind chill is to reduce any warmer objects to the ambient temperature more quickly. It cannot, however, reduce the temperature of these objects below the ambient temperature, no matter how great the wind velocity. For most biological organisms, the physiological response is to maintain surface temperature in an acceptable range so as to avoid adverse effects. Thus, the attempt to maintain a given surface temperature in an environment of faster heat loss results in both the perception of lower temperatures and an actual greater heat loss increasing the risk of adverse effects such as frostbite and death.
  The index shows the way your skin feels to the temperature on a calm day. For example, if the outside temperature is -5°C and the wind chill is -7, it means that your face will feel as cold as it would on a calm day when the temperature is -7°C.
• WIND DIRECTION (in degrees and letters, e.g. NE for North-East), current and average value for the day;
• WIND SPEED (in Km/hour), average value for the last fifteen minutes, maximum and minimum value for the day;
• RAIN (in millimeters), current, total and rate value for the day (in mm/day);
• HUMIDITY (in percentage), current, maximum and minimum value for the day;
  Relative humidity is the ratio of the actual amount of water vapour in the air to the amount it could hold when saturated expressed as a percentage OR the ratio of the actual vapour pressure to the saturation vapour pressure expressed as a percentage. The amount of water vapour the air can hold increases with temperature. Relative humidity therefore decreases with increasing temperature if the actual amount of water vapour stays the same.
• ATMOSPHERIC PRESSURE (in hectopascal), average value for the last fifteen minutes, maximum and minimum value for the day;
• SOLAR RADIATION (in Kw/m2), average value for the last fifteen minutes and total value for the day.
• DEW POINT (in degrees Celsius °C), average value for the last fifteen minutes, maximum and minimum value for the day.
  Dew points indicate the amount of moisture in the air. The higher the dew points, the higher the moisture content of the air at a given temperature. Dew point temperature is defined as the temperature to which the air would have to cool (at constant pressure and constant water vapour content) in order to reach saturation. A state of saturation exists when the air is holding the maximum amount of water vapour possible at the existing temperature and pressure. When the dew point temperature and air temperature are equal, the air is said to be saturated. Dew point temperature is NEVER GREATER than the air temperature.

ii    Images from the webcam

Next to the weatherstation a webcam has been mounted with a view over the Palatine Hill. Every 5 minutes a new image is recorded. Webcams from some other major Italian towns and tourist locations are also provided.

iii    Images from meteorological satellites

Every 30 minutes and every 3 hours, images derived from meteorological satellites are downloaded. The satellites include METEOSAT, operated by EUMETSAT, and GOES, operated by NOAA.
The images are recorded in the infrared part of the spectrum. Infrared images represent the infrared radiation emitted by the clouds or by the earth surface. They are actually measurements of temperature. For an infrared picture, warmer objects appear darker than colder objects. Cloud free areas will typically be dark, but also very low clouds and fog may appear dark. Most other clouds are bright. High level clouds are brighter than lower level clouds.

iv    Weather forecasts

Every day a number of weather forecasts for various areas of the world are downloaded from the Internet.

For further information and comments please contact FAO-Climate@fao.org