Casiguran, Aurora Climatological Normal Values

Rainfall (column 2) The amount of precipitation (rain, hail, etc.) expressed in millimeters depth, of the layer of the water which has fallen. Rainy days (column 3) A rainy day is defined as a period of 24 hours beginning at 8AM to 8 AM of the next day during which 0.1 mm of rain is recorded. Maximum Temperature (column 4) The maximum temperature in °C recorded for the day, usually occurring in the early afternoon. Minimum Temperature (column 5) The minimum temperature in °C recorded for the day, usually occurring during early hours of the morning (before sunrise). Mean Temperature (column 6) Mean Temp. = Maximum + Minimum / 2 Dry Bulb Temperature (column 7) It gives the air temperature in °C at the time of observation. Wet Bulb Temperature (column 8) It gives the temperature in °C that an air parcel would have if cooled adiabatically to saturation at constant pressure by evaporating water in it. Dew Point Temperature(column 9) The temperature in °C at a given pressure, to which the air must be cooled to become saturated. It is the temperature when atmospheric moisture begins to condense to liquid forming “dew” upon objects. Vapor Pressure(column 10) Denotes the partial pressure of water vapor in atmosphere. As the water evaporates, additional water vapor is introduced into space above and pressure increases slightly as the new vapor is added. The increasing pressure is due to an increase in the partial pressure of water vapor. Relative Humidity (column 11) The ratio of the amount of water vapor actually in the air to the maximum amount the air can hold at that temperature. Mean Sea Level Pressure (column 12) The force exerted by the weight of the atmosphere on a unit area at the mean sea level. It is also the atmospheric pressure at mean sea level. Prevailing Winds (column 13 & 14) The prevailing wind direction most frequently observed during a given period while the average wind speed in meters per second is the arithmetic average of the observed wind speed. Cloud (column 15) The amount of cloud present in the sky, expressed in oktas of the sky cover. Okta is the function used in denoting cloud amount and is equal to 1/8 of the whole sky. Days with Thunderstorm (column 16a) A thunderstorm day is defined as an observational day during which thunder is at station. Days with Lightning (column 16b)  A day with lightning is reported whenever lightning is observed.