PREFIXES
Units can be used as such or in multiples:
|
Tera |
(T) and which is |
1012 |
|
Giga |
(G) |
109 |
|
Mega |
(M) |
106 |
|
Kilo |
(k) |
103 |
|
Hecto |
(h) |
102 |
|
Deca |
(da) |
101 |
|
Deci |
(d) |
10-1 |
|
Centi |
© |
10-2 |
|
Milli |
(m) |
10-3 |
|
Micro |
(m) |
10-6 |
|
Nano |
(n) |
10-9 |
|
Pico |
(p) |
10-12 |
|
Femto |
(f) |
10-15 |
|
Atto |
(a) |
10-18 |
TEMPERATURE
Standard unit: degree Celsius (°C)
|
degree Fahrenheit (°F) |
(°C) = (°F-32) 5/9 |
|
Kelvin (K) |
1K = (°C) + 273.16 |
PRESSURE (air pressure, vapour pressure)
Standard unit: kilopascal (kPa)
|
millibar (mbar) |
1 mbar = 0.1 kPa |
|
bar |
1bar = 100 kPa |
|
centimetre of water (cm) |
1 cm of water = 0.09807 kPa |
|
millimetre of mercury (mmHg) |
1 mmHg = 0.1333 kPa |
|
atmospheres (atm) |
1 atm = 101.325 kPa |
|
pound per square inch (psi) |
1 psi = 6.896 kPa |
WIND SPEED
Standard unit: metre per second (m s-1)
|
kilometre per day (km day-1) |
1 km day-1 = 0.01157 m s-1 |
|
nautical mile/hour (knot) |
1 knot = 0.5144 m s-1 |
|
foot per second (ft s-1) |
1 ft/s = 0.3048 m s-1 |
RADIATION
Standard unit: megajoule per square metre and per day (MJ m-2 day-1) or as equivalent evaporation in mm per day (mm day-1)
|
equivalent evaporation (mm/day) |
1 mm day-1 = 2.45 MJ m-2 day-1 |
|
joule per cm2 per day (J cm-2 day-1) |
1 J cm-2 day-1 = 0.01 MJ m-2 day-1 |
|
calorie per cm2 per day (cal cm-2 day-1) |
1 cal = 4.1868 J = 4.1868 10-6 MJ |
|
|
1 cal cm-2 day-1 = 4.1868 10-2 MJ m-2 day-1 |
|
watt per m2 (W m-2) |
1 W = 1 J s-1 |
|
|
1 W m-2 = 0.0864 MJ m-2 day-1 |
EVAPOTRANSPIRATION
Standard unit: millimetre per day (mm day-1)
|
m3 per hectare per day (m3 ha-1 day-1) |
1 m3 ha-1 day-1 = 0.1 mm day-1 |
|
litre per second per hectare (1 s-1 ha-1) |
1 l s-1 ha-1 = 8.640 mm day-1 |
|
equivalent radiation in megajoules per square metre per day (MJ m-2 day-1) |
1 MJ m-2 day-1 = 0.408 mm day-1 |
