Degree-days

Degree days are number of days past treatment multipHed by the water temperature (°C). 

Withdrawal periods are in days or degree days e.g. 400 degree days is 20 days at 20 °C. 

The quantity I, (T To(t))dt is named the degree day and is normally calculated for each month but also on a yearly basis. It depends on the climate where the industrial building is situated. This means that different geographic positions have different degree days. From the definition we also see that the degree day depends on the assumed indoor air temperature, which is assumed constant. 

Degree-days Temperature data recorded over a 24-hour period as deviation from a certain base temperature used to deter mine the operating costs of a heating or air conditioning system depending on the external climatic conditions. 

Degree-days are calculated by multiplying the water temperature by the number of days. 

In actual installations these systems have been shown to use about 45 to 50% of the electricity consumed in a similar house with conventional electric resistance heating. It is more efficient than a conventional air-to-air heat pump system, since the heat source is maintained at a constant, known temperature. In moderate cold climates with 6,000 degree-days, an ACEs uses about 25% less electricity than a conventional heat pump with... 

Weekly values of average temperature (AVETEMP) and of heating (HEATDD) and cooling (COOLDD) degree days were calculated from the daily values measured in Central Park (in Manhattan) obtained from the National Weather Service. 

Determining MRLs in fish presents particular problems because the metabolic rates of drugs are partly governed by fish body temperature, which is, in turn, dependent upon the ambient temperature of the water in which they live the cooler the water, the longer residue depletion takes. For this reason, residue depletion studies in fish are usually conducted at several temperatures chosen to represent the range of temperatures to which they will be exposed under normal farming conditions. Withdrawal periods are then quoted in degree days, a unit that is a function of both time and temperature. 

Megyesi, M. S., Nawrocki, S. P., and Haskell, N. H. (2005). Using accumulated degree-days to estimate the postmortem interval from decomposed human remains. /. Forensic Sci. 50, 618-626. 

Growing degree days Cumulative total of mean daytime temperature in °C above a baseline temperature (for Jerusalem artichoke typically 0°C). The value increases throughout the growing season with final values depending upon location and length of the growing season 3000°C (Italy) Monti et al., 2005... 

I recently calculated that in my home province of Ontario growing degree days may increase by 10 to 25 per cent by 2050 AD, with a net increase in the growing season of five to seven weeks (Hare, 1982). This would allow the penetration of typical corn belt agriculture into southern areas of Ontario. On the Canadian Prairies, now dominated by spring wheat-barley-oilseeds cultivation, winter wheat might become the dominant crop. These gains would, however, be lost if rainfall failed to make up for the increased water demands that are implied. 

To a large extent, temperature regulates pest development. Scientists use units of measurements called degree days to track heat accumulation over time and predict the local appearance of various pests. The degree day formula assigns a value to each day s maximum and minimum temperature and com-... 

Bonhomme R. Bases and limits to using degree.day units. European Journal of Agronomy 2000 13(1) 1-10. 

Between 1734 and 1742, Reaumur wrote six volumes of Memoires pour servir a I histoire des insectes (Memoirs serving as a natural history of insects). Although unfinished, this work was an important contribution to entomology. He also noticed that crayfish have the ability to regenerate lost limbs and demonstrated that corals were animals, not plants. In 1735 he introduced the concept of growing degree-days, later known as Reaumur s thermal constant of phenology. This idea led to the heat-unit system used today to study plant-temperature relationships. 

Fig. 2. Total lipid in cultured Atlantic salmon (Salmo salar) over their life cycle. Adapted from ref. 123. Data points 1 -8 represent doubling of degree days from fertilization until near hatching 12-26 represent approximate doubling of body weight at each point. Lipids determined gravimetrically after Soxhlet extraction from dried tissues.

---