FORMULA SHELF
7 of 370
The arithmetic behind the work: what to measure, what to type in, and what the answer comes out as. Every formula says what the symbols mean and gives a worked example, so you can check it against a job you have already done.
SHELVES
Weather
7 formulas
A quick dew-point estimate. When dew point is close to air temperature, expect condensation.
20 C at 60% RH has a dew point near 12 C.
Convenience only. Double-check the result against the worked example or a second method before you use it.
Estimating water loss from soil and crops using a simple evaporation pan.
10 mm pan loss at 0.75 is 7.5 mm of crop water use.
Tracking crop and pest development against temperature rather than the calendar.
Max 24, min 10, base 5 gives 12 GDD for the day.
How hot it feels when humidity stops sweat evaporating. Watch workers and livestock.
32 C at 70% humidity can feel near 40 C.
Sizing a tank, drain or dam from roof or yard runoff.
20 mm on a 100 m2 roof at 0.9 = 1.8 m3.
Drying grain, hay, curing concrete and judging spray conditions.
Half the saturation vapour pressure means 50% RH.
How cold it feels on exposed skin. Important for livestock, workers and young stock.
0 C with 30 km/h wind feels like -6 C.
SOURCES & PROVENANCE
1 listed
This page is an AI-organised index. The label means the grouping and cross-links were compiled with AI; the information itself comes from the public-domain books, reports and manuals listed below. Open any source to read the local copy or follow the link to the original publication.