Agriculture Reference
In-Depth Information
1 kilopascal (kPa) = 1000 Pa
1 pascal (Pa)
= 1 newton per square metre (N m
−2
)
1 milibar (mb)
= 100 Pa
1 centibar (cb)
= 1000 Pa = 1 kilopascal (kPa)
1 bar (b)
= 0.987 atmospheres = 0.1 megapascales (MPa)
1 joule (J) = 0.239 calories (cal)
1 calorie (cal) = 4.18 joules (J)
1 watt (W) = 1 joule per second (J s
−1
)
1 kilowatt-hour (kWh) = 3600 kilojoules (kJ)
1 kilowatt-hour (kWh) = 3.6 megajoules(MJ)
1 kilowatt-hour (kWh) = 860 kilocalories (kcal)
Solar constant:
1353 W m
−2
= 4871 kJ m
−2
h
−1
=
1940 cal cm
−2
min
−1
= 1940 Ly min
−1
Radiation intensity (irradiance):
1 W m
−2
= 1.434 10
−3
cal cm
−2
min
−1
1 cal cm
−2
min
−1
= 697.3 W m
−2
Cumulated radiation:
1 langley (Ly) = 1 cal cm
−2
= 41.84 kJ m
−2
1 kilolangley (kLy) = 1000 Ly
1 kWh m
−2
= 3.6 MJ m
−2
1 kWh m
−2
= 860 kcal m
−2
= 86 Ly
1 litre per square metre (l m
−2
) = 1 mm = 10 m
3
ha
−1
n (nano) = 10
−9
m (micro) = 10
−6
m (milli) = 10
−3
k (kilo) = 10
3
M (mega) = 10
6
G (giga) = 10
9