Data Info

Global Solar Radiation (GSR) or Solar Radiation

This is a calculation of solar radiation energy being received at the earth's ground surface from sunlight energy inputs. The sensors used are a thermopile based global solar radiation sensor which put simply interpret a broad band of energy wavelength being received between 300 nm to 2800 nm to produce one estimate of energy input. This calculation is stated in unit energy terms as Watts of energy received per square metre (W/m2). These estimates are then reported as averages over the 15 minute monitoring period or as maximum incidences of solar radiation inputs received in W/m2. Further estimates are available in exported data sets between minutely and daily data.

Reference Crop Evapo-transpiration (ETo mm/ETo mm raw)

This is a calculated data set that uses a number of weather station data parameters within a complex calculation to determine likely water vapour loss from a hypothetical plant surface on a daily basis. This calculation is stated in mm of moisture loss. The Penman-Monteith calculation that is used produces an estimate of inferred water loss from a 'well-watered' grassy surface at 0.12 m in height. To utilize ETo data for estimating individual crop water loss the user needs to additionally use a crop coefficient (Kc) factor to 'adjust' the daily ETo estimates to match proximal crop water usage for a target crop. Users should ensure that their crop coefficients are industry standard and matched to the region where they are being applied.

Daylight Hours and Daylight Hours raw

This is a simplified approach to calculating daylight hours using thresholds of global solar radiation (GSR) above ~5 W/m2 reported in 15 minute intervals which are then calculated back to hours of daylight. These estimates are available either through the data export function or select periods of daylight hours can be sourced through the calculator function.

Degree Days

Degree Days is a simple calculation useful for appreciating or calibrating an approach to estimating plant or crop growth rates, including durations to fruiting maturity. The calculation used essentially compares daily maximum and minimum temperatures against a base temperature (in this case 10 degrees Celsius) to derive estimates of daily 'Degree Days' – elementally being accumulation of hours above the temperature threshold. As such a user of Degree Days can assemble generic data sets that can be useful in comparing conditions conducive to cropping or fruiting conditions where 10 degrees Celsius is a satisfactory baseline minimum temperature. For more exacting crop specific calculations the Growing Degree Days calculator is recommended.

Growing Degree Days

Growing Degree Days is the progression of the basic Degree Days function which utilizes specific crop minimum temperature thresholds to provide estimates of heat units stated as 'Growing Degree Day' accumulations. A number of commonly accepted base temperature thresholds are available beyond the 10 degrees Celsius baseline of Degree Days calculation. These are available in the 'calculators' function with the option to nominate a specific temperature figure also being available. The results of Growing Degree Days ensures that only accumulations of hours above the baseline nominated temperature are considered in the accumulation.

Delta-T

Is a calculation that has been designed to optimise spray decision making when considering a standardised relationship between temperature, relative humidity and spray droplet life. Delta-T degrees reveal how optimal current temperature and humidity conditions really are in combination for spray droplet life. Delta-T degrees need to be aligned with a standardised chart of the relationship of Delta-T degrees to relative humidity and current temperatures (often called dry bulb temperatures). Usage of this chart and current Delta-T degree estimates will show whether current Delta-T degree estimates align with the designated ranges for spraying which are between 2-8 degrees Delta-T. It is important to note that operators need to additionally factor wind conditions into their spraying decision making. Delta-T reveals how optimal current conditions are for droplet life.

Frost Hours

Frost hours is a simple reporting of the accumulated hours experienced over a 24 hour period of conditions below 2 degrees Celsius. Users should consider that a reporting day period for a weather station runs from 9.00 a.m. on day 1 to 8.59 a.m. on day 2. This for the user could potentially screen out considerations of frost that technically occurred between 12.00 a.m. and 9.00 a.m. on the true day 1 period. Understanding this will help reduce confusion in reviewing reported estimates of frost accumulation.

Leaf Wetness

Is an estimation of the wetness of a leaf area approximately the size of a common variety wine grape leaf that as a percentage of total surface area. This together with the reporting period which can either be daily or 15 minutely thereby provides not only a measure of the intensity of leaf wetness by percentage but also the length of time that foliage was wet, an essential in estimating foliar disease risk in combination with other factors such as temperature, relative humidity and wind speed.

Chill Hours and Chill Portions

In climates where winter periods may have random warming periods the effects on crops that require extended periods below 7 to 10 degrees Celsius as 'vernalisation' periods for optimum flowering and fruiting potential are considered detrimental. To calculate the effect of annual climatic conditions on these crop types a user can use the chill hours and chill portions calculator which provides two estimates. The first estimate is a simplistic accumulation of known hours below either 7 or 10 degrees Celsius – common baselines used for a mixture of orchard tree species. Chill portions is a more advanced calculation that is dynamic in that after having calculated chill hours the model approach will assess over the period whether intervening conditions (after the chill hour cold periods) experienced within the day period were warm enough to reverse the benefits to vernalisation of the chill hours previously accumulated. As such chill portions becomes the true final consideration of how effective conditions really are for specific crop types with regards to vernalisation. Users should not just use chill hours but both estimates.

Apparent Temperature

Provides an estimate of the impacts of current temperature (degrees Celsius), humidity (percentage), wind speed (taken at 2 m as metres/second) and other factors on the heat balance of the human body. Put simply apparent temperature can be considered as a 'feels like' parameter that models what the conditions may feel like rather than what it is believed conditions may be like just through the singular appraisal, for example of temperature on its own.

Dew Point

Is related to both temperature and relative humidity and is stated in degrees Celsius. Put simply the dew point in degrees Celsius is the temperature to which a current state air mass would need to be cooled to achieve both saturation and the condensation of the water vapour to achieve a dew event. As the ambient temperature and the dew point temperature become closer with cooling and relative humidity's increase there is a greater likelihood that there will be a dew. This dew in more extreme conditions can subsequently lead to a frost event when ground surfaces are very cold and conditions very still, i.e. a lack of air flow.