GLOSSAIRE
STATION MÉTÉO VANTAGE PRO 2
| Alternative temperature | °C | The weather station allows for more temperature sensors in addition to the always present inside- and outside sensors. This particular alternative temperature probe is positioned outside the house at a shielded position facing the south. Its readings are merely a measure for the temperature of the terrace of the house where the weather station is located. It is reported, but not used as the basis for any calculation. Because of its position under the terrace roof, the measured values are generally higher than those of the far more representative main outside temperature sensor. |
| Altitude | The altitude of this weather station is approximately 15 meters above mean sea level. Altitude affects only the barometric pressure sensor in the weather station. The pressure sensor operates at altitudes up to 12,000 feet (~ 6667 meters). The sunrise/sunset calculation is also influenced by the altitude. | |
| Barometric pressure | mb | The weight of the air that makes up our atmosphere exerts a pressure on the surface of the earth. This pressure is known as atmospheric pressure. Generally, the more air above an area, the higher the atmospheric pressure, this, in turn, means that atmospheric pressure changes with altitude. For example, atmospheric pressure is greater at sea-level than on a mountaintop. To compensate for this difference and
to facilitate comparison between locations with different altitudes, atmospheric pressure is generally adjusted to the equivalent
sea level pressure. This adjusted pressure is known as barometric pressure. In reality, the
weather station measures atmospheric pressure and translates consistently atmospheric pressure into barometric pressure.
The measurement unit is millibar, and 1 millibar = 1 HectoPascal
(hPa ) Barometric pressure changes with local weather conditions, making barometric pressure an extremely important and useful weather forecasting tool. High pressure zones are generally associated with fair weather while low pressure zones are generally associated with poor weather. For forecasting purposes, however, the absolute barometric pressure value is generally less important than the change in barometric pressure. In general, rising pressure indicates improving weather conditions while falling pressure indicates deteriorating weather conditions. |
| Beaufort scale | A system of estimating and reporting wind speeds. It is based on the Beaufort Force or Number, which is composed of the wind speed, a descriptive term, and the visible effects upon land objects and/or sea surfaces. The scale was devised by Sir Francis Beaufort (1777-1857), hydrographer to the British Royal Navy.
Conversion table km/hr to Beaufort: Speed >= 1 And < 6 km/hr Beaufort = 1 Speed >= 6 And < 12 Beaufort = 2 Speed >= 12 And < 20 Beaufort = 3 Speed >= 20 And < 29 Beaufort = 4 Speed >= 29 And < 39 Beaufort = 5 Speed >= 39 And < 50 Beaufort = 6 Speed >= 50 And < 62 Beaufort = 7 Speed >= 62 And < 75 Beaufort = 8 Speed >= 75 And < 89 Beaufort = 9 Speed >= 89 And < 103 Beaufort = 10 Speed >= 103 And < 117 Beaufort = 11 Speed >= 117 Beaufort = 12 |
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| Console | The console is the processing- and storage-unit of the weather station. It also represents the human interface to the system and deploys a large LCD screen for the display of values and graphs. It is installed inside the house in France and receives the actual data from the outside sensors through three wireless connections. It is connected to the public telephone network for communication with the outside world. In order to obtain complete independence from the electric mains, the console and communication equipment are powered through an accumulator with solar panel support. | |
| Cooling degree-days | dd | Cooling degree-days is a unit of measure for calculating the effect of temperature on the consumption of energy (e.g. electricity) to cool a location. Temperature plays an important part in the consumption of energy to cool a house or other structures. |
| Dew point | °C | Dew point is the temperature to which air must be cooled for saturation (100% relative Humidity) to occur, providing there is no change in water content. The dew-point is an important measurement used to predict the formation of dew, frost, and fog. If dew-point and temperature are close together in the late afternoon when the air begins to turn colder, fog is likely during the night. Dew point is also a good indicator of the air s actual water vapor content, unlike relative humidity, which takes the air s temperature into account. High dew point indicates high vapor content; low dew-point indicates low vapor content. In addition a high dew-point indicates a better chance of rain and severe thunderstorms. You can even use dew-point to predict the minimum overnight temperature. Provided no new fronts are expected overnight and the afternoon Relative Humidity ≥ 50%, the afternoon s dew point gives you an idea of what minimum temperature to expect overnight, since the air is not likely to get colder than the dew-point anytime during the night. |
| Evapo Transpiration | mm | Evapo Transpiration (ET) is a measurement of the amount of water vapor returned to the air in a given area. It combines the amount of water vapor returned through evaporation (from wet vegetation surfaces and the stoma of leaves) with the amount of water vapor returned through transpiration (exhaling of moisture through plant skin) to arrive at a total. Effectively, Et is the opposite of rainfall, and it is expressed in the same units of measure (Inches, millimeters). The Vantage Pro uses air temperature, relative humidity, average wind speed, and solar radiation data to estimate ET. (ET is calculated once an hour on the hour.) |
| Gale | Wind with speeds from 28 to 55 knots (52 to 102 kilometers per hour). In 1964, the World Meteorological Organization defined the categories as near gale (52 to 62 km/h), gale (63 to 74 km/h), strong gale (63 to 74 km/h), and storm (75 to 102 km/h). | |
| Growing degree-days | Because temperature plays an important part in the rate of development of plants and many pests (especially insects), a measurement including the accumulation of heat with passing time is necessary to predict maturation. Growing degree-days provide a measure for calculating the effect of temperature on the development of plants and/or pests. One growing degree-day is the amount of heat that accumulates when the temperature remains one degree above the base developmental threshold for 24 hours. One growing degree-day is also the amount of heat that accumulates when the temperature remains 24° above the base threshold for 1 hour. (What about Heating and Cooling Degree-days?) Note that there are no negative degree-days. If the temperature remains below the threshold, there is no degree-day accumulation.
Unlike strict time predictions of plant/pest development, growing degree-day predictions hold true regardless of location or temperature fluctuations. As long as you know the number of degree-days necessary for plant/pest development, you may use degree-days as an accurate predictor. For example, you may know that it takes, in general, three weeks for a specific pest to develop. What you will find, however, is that the pest may take 4 weeks to develop in cooler weather and only 2 weeks to develop in warmer weather. The time prediction can be off by up to a week in this example, while the degree day prediction should result in far greater accuracy |
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| Gust | km/hr | A sudden significant increase in or rapid fluctuations of wind speed. The duration is usually less than twenty seconds. |
| Heat Index | °C | The Heat Index uses the temperature and the relative
humidity to determine how hot the air actually feels. When humidity is low, the apparent temperature will be lower than the air temperature, since perspiration evaporates rapidly to cool the body. However, when humidity is high (i.e., the air is saturated with water vapor) the apparent temperature feels higher than the actual air temperature, because perspiration evaporates more slowly.
Note: The weather station measures Heat Index only when the air temperature is above 14° C, because it s insignificant at lower temperatures. (Below 14°, Heat Index = the air temperature.) The Heat Index is not calculated above 52° C. |
| Heating degree-days | dd | Heating Degree-days is a unit of measure for calculating the effect of temperature on the consumption of energy (e.g. heating oil) to heat a location, essentially the opposite of Cooling Degree-days. |
| Highest rain rate | mm/hr | The highest rain rate detected over a certain period. The value is expressed in mm's per hour. The highest ever measured by the weather station is 82 mm/hour. |
| Highest wind speed direction | The direction the wind was blowing from when the highest wind speed was measured. | |
| Humidity | % | Relative humidity is a percentage of total air saturation by water vapor. The amount of water vapor that it takes to saturate the air (i.e. 100%) increases exponentially as temperature increases. When the temperature increases the percentage of total air saturation decreases and vice versa. |
| Inside humidity | % | The average humidity inside the house for a certain time period. The sensor is located inside the stations' console at a non-representative, but constant position. |
| Inside temperature | °C | The average temperature inside the house for a certain time period. The sensor is located inside the stations' console at a non-representative, but constant position. Because of the window- and wall isolation of the house, the inside temperature follows the outside one with a considerable time delay. |
| Kelvin temperature scale | °K | A temperature scale with the freezing point of +273°K (Kelvin) and the boiling point of +373° K. It is used primarily for scientific purposes. Also known as the Absolute Temperature Scale. Proposed in 1848 by William T. Kelvin, 1st Baron of Largs (1824-1907), Irish-born Scottish physicist and mathematician. |
| Lowest temperature | °C | Is defined as the lowest outside temperature reached in a time period. Note that this parameter is measured by the weather station itself, and is not derived from the low of the average outside temperatures in the database. |
| Outside temperature | °C | The temperature as measured by the main outside sensor. In addition, separate information is also collected about the measurement during day hours (as defined by sunrise and sunset), and during night hours. |
| Rain | mm | Precipitation in the form of liquid water droplets greater than 0.5 mm. If widely scattered, the drop size may be smaller. The intensity of rain is based on rate of fall. "Very light" (R--) means that the scattered drops do not completely wet a surface. "Light" (R-) means it is greater than a trace and up to 0.25 mm an hour. "Moderate" (R) means the rate of fall is between 0.25 to 0.75 mm per hour. "Heavy" (R+) means over 0.75 mm per hour.
The weather station measures the amount of rain in mm per time unit. 1 mm rain is equivalent to 1 liter per square meter. |
| Rain by day | mm | The amount of rain measured by the weather station in day time (between sunrise and sunset). The value has no meteorological meaning, but is merely determined to check the holiday weather conditions. |
| Rain rate | mm/hr | The average amount of rain measured in a time period. The weather station expresses this value in mm's per hour. |
| Rain storm | Rain Storm displays the rain total of the last rain event. It takes two rain clicks to begin a storm event and 24 hours without rain to end a storm event. | |
| Rainy hours by day | hr | The amount of rainy hours in day time. |
| Reception quality | % | The Reception rate shows the percentage of data packets that have been successfully received by the Vantage Pro console. It is a measure of the reception quality. Values above 90% are normal when the house is not occupied, otherwise the value can be as low as 20%. This is probably caused by interfering transmitters - e.g. notebook computers, or other MHz transmitters. |
| Sea fog | A type of advection fog which forms in warm moist air cooled to saturation as the air moves across cold water. | |
| Soil moisture | cbar | The moisture
content of the upper layer of a soil. The Vantage Pro measures the soil moisture
using a Watermark sensor of Irrometer Company. This sensor uses resistance to
indicate water availability. The following table can act as a general guid to
interprete the readings: Centibar Condition ====== ======= 0-10 Saturated soil. Occurs for a day or two after irrigation 10-20 Soil is adequately wet 30-60 Usual range to irrigate - except heavvy clay soils 60-100 Usual range to irrigate heavy clay soils 100-200 Soil is becoming dangerously dry |
| Soil Temperature | °C | The temperature of the soil at the depth of the soil moisture sensor. The temperature is also used by the weather station to compensate the moisture reading. |
| Solar energy | L | The amount of accumulated solar radiation energy over a period of time is measured in Langleys.
1 Langley = 11.622 Watt-hours per square meter = 3.687 BTUs per square foot = 41.84 kiloJoules per square meter |
| Solar radiation | W/m2 | What we call "current solar radiation" is technically known as Global Solar Radiation, a measure of the intensity of the sun s radiation reaching a horizontal surface. This irradiance includes both the direct component from the sun and the reflected component from the rest of the sky. The solar radiation reading gives a measure of the amount of solar radiation hitting the solar radiation sensor at any given time, expressed in Watts per square meter (W/m2). The value logged by WeatherLink is the average solar radiation measured over the archive interval. The Solar Radiation Sensor detects radiation at wavelengths of 300 to 1100 nanometers. |
| Sun hour | hrs | The number of sunny hours over a certain period of time. An hour is defined as sunny in case the average solar radiation over the hour exceeds "x" Watts per square meter. The "x" depends on the month of the year. The table below gives an approximation of the limits per mid-month. These are for illustration purposes only; the actual limits are calculated for each individual date.
Month Values: Jan 190 Feb 230 Mar 270 Apr 310 May 340 Jun 360 Jul 370 Aug 365 Sep 345 Oct 315 Nov 270 Dec 205 |
| Sun Percentage | % | The percentage sun hours in relation to the number hours between sunrise and sunset. |
| Sunrise | The daily appearance of the sun on the eastern horizon as a result of the earth's rotation. In the United States, it is considered as that instant when the upper edge of the sun appears on the
sea level horizon. In Great Britain, the center of the sun's disk is used instead. Time of sunrise is calculated for mean sea level.
The time depends on the position on earth of the observer, and the calendar date of the observation. The position of the weather station is: 45° 24" 0' North and 1° 12" 0' West |
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| Sunset | The daily disappearance of the sun below the western horizon as a result of the earth's rotation. In the United States, it is considered as that instant when the upper edge of the sun just disappears below the
sea level horizon. In Great Britain, the center of the sun's disk is used instead. Time of sunset is calculated for mean sea level.
The time depends on the position on earth of the observer, and the calendar date of the observation. The position of the weather station is: 45° 24" 0' North and 1° 12" 0' West |
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| Temperature | °C | The measure of molecular motion or the degree of heat of a substance. It is measured on an arbitrary scale from absolute zero, where the molecules theoretically stop moving. It is also the degree of hotness or coldness. In surface observations, it refers primarily to the free air or ambient temperature close to the surface of the earth. In Europe the temperature is expressed in degrees
Celsius, whereby melting ice is defined to be zero degrees, and boiling water 100 degrees. In the USA and some other countries, the temperature is expressed in degrees Fahrenheit. The conversion formula is: C=(F-32)*5/8
In the weather station the outside temperature is measured 2 meters above surface level. The sensor is located inside a temperature shield which is mounted on the east side of the house. |
| THSW index | °C | THSW (Temperature - Humidity - Sun - Wind). Like Heat Index, the THSW Index uses humidity and temperature to calculate an apparent temperature. In addition, THSW incorporates the heating effects of direct solar radiation and the cooling effects of wind on our perception of temperature. |
| UV index | idx | The UV Index measures the intensity of UV. It uses a scale of 0 to 16 to rate the current intensity of UV. The UV value logged by WeatherLink is the average UV measured during the archive interval. The UV sensor detects Ultraviolet Radiation at wavelengths of 290 to 390 nanometers. The US EPA categorizes the UV Index values as shown below:.
0-2 Minimal 3-4 Low 5-6 Moderate 7-9 High 10+ Very High |
| UV med | med | MED stands for Minimum Erythemal Dose, defined as the amount of sunlight exposure necessary to induce a barely perceptible redness of the skin within 24 hours after sun exposure. In other words, exposure to 1 MED will result in a reddening of the skin. Because different skin types burn at different rates, 1 MED for persons with very dark skin is different from 1 MED for persons with very light skin.
Note: The Vantage Pro assumes Skin Type II: White. Always burns easily, tans minimally |
| Wind | Air that flows in relation to the earth's surface, generally horizontally. There are four areas of wind that could be measured: direction, speed, character (gusts and squalls), and shifts. Surface winds are measured by wind vanes and anemometers, while upper level winds are detected through pilot balloons, rawin, or aircraft reports.
The weather station measures direction, speed and gusts speed. Its anemometer is located two meters above the rooftop of the house. |
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| Wind chill | °C | Wind chill takes into account how the speed of the wind affects our perception of the air temperature. Our bodies warm the surrounding air molecules by transferring heat from the skin. If there s no air movement, this insulating layer of warm air molecules stays next to the body and offers some protection from cooler air molecules. However, wind sweeps that comfy warm air surrounding the body away. The faster the wind blows, the faster heat is carried away and the colder you feel. Above 32.8 °C, wind movement has no effect on the apparent temperature, so wind chill is the same as outside temperature. |
| Wind direction | The direction from which the wind is blowing. For example, an easterly wind is blowing from the east, not toward the east. It is reported with reference to true north, or 360 degrees on the compass, and expressed to the nearest 10 degrees, or to one of the 16 points of the compass (N, NE, WNW, etc.). | |
| Wind run | km | Wind run is a measure of the amount of wind which passes a given point during the measurement period. To calculate wind run, multiply the speed by the length of time in the measurement period. For example 10 km/hr for 12 hours would be 120 kilometers of wind run. Since the basic measuring period of the present weather station is one hour, the wind run is equal to the wind speed. |
| Wind speed | km/hr | The wind speed is measured with a so-called anemometer and is determined by counting rotation pulses over a sample period. The sample period is 2.25 seconds. The number of pulses per sample period is equal to the wind speed in miles per hour. In the database the wind speed is expressed in km/hr. The conversion factor for some frequently used units is as follows: 1 MPH = 1.6093 kph = 0.4470 m/sec = 0.8690 knots. The conversion to the well-known Beaufort scale is less obvious. |