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Solar Radiation Units and Conversion |
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International system of units
The International System of Units, abbreviated SI (from the French Système International), is the internationally-agreed system of measurement.
Angles: Plane angles are expressed in radian (rad), or degrees, or sexagesimal degrees (degrees, minutes, seconds). Convert from one unit to another
Energy: Energy, work, quantity of heat are expressed in Joule (J). It can be expressed by unit of surface: J/m2, J/cm2. Irradiation is the energy received per area. Other units are Wh (Watt hour), calorie, therm, Langley. Convert from unit to another
Power: Power, radiant flux are expressed in Watt (W). Irradiance is defined as a power received per area; it is expressed in W m-2 (watt per square meter). Convert from unit to another
Pressure :Pressure is expressed in Pascal (Pa). In meteorology, the unit hPa (hecto-Pascal) is commonly used; it is 100 times a Pascal. It replaces the millibar unit and they are equivalent. Another unit is the "atmosphere". Convert from unit to another
Conversion factors
The following tables give conversion factors to convert units into others. See an example
| To convert from | Into | Multiply by |
| degrees (°) | radians (rad) | 1.745329 E-02 |
| radians (rad) | degrees (°) | 57.29578 |
| minutes (’) | degrees (°) | 0.0167 |
| seconds (") | degrees (°) | 1.6667 E-04 |
| degrees, minutes, seconds | degrees with decimals | degrees + minutes/60 + seconds/3600 |
| To convert from | Into | Multiply by |
| calorie (cal) | Joule (J) | 4.1868 |
| Watt second (W s) | Joule (J) | 1 |
| Watt hour (Wh) | Joule (J) | 3.6 E+03 |
| Joule (J) | calorie (cal) | 0.2388 |
| Joule (J) | Watt hour (Wh) | 0.2778 E-03 |
| therm (Europe) | Joule (J) | 1.05506 E+08 |
| Watt hour per square meter (Wh / m2) | Joule per square centimeter (J / cm2) | 0.36 |
| Joule per square centimeter (J / cm2) | Watt hour per square meter (Wh / m2) | 2.778 |
| Joule per square meter (J / m2) | Watt hour per square meter (Wh / m2) | 0.2778 E-03 |
| Langley (Ly) | Wh / m2 | 11.6 |
| Langley (Ly) | J / m2 | 41.84 E+03 |
| kLy / year | W / m2 | 1.33 |
| To convert from | Into | Multiply by |
| atmosphere standard (atm) | Pascal (Pa) | 1.01325 E+05 |
| atmosphere standard (atm) | hecto-Pascal (hPa) | 1.01325 E+03 |
| Pascal (Pa) | atmosphere standard | 0.98692 E-05 |
How to Use the Conversion Factors: Each entry of the above tables is to be interpreted as follows.
| To convert from | Into | Multiply by |
| Watt hour (Wh) | Joule (J) | 3.6 E+03 |
means 1 Wh = 3600 J. Thus to express, for example, the energy E = 6.5 Wh in J, write
E = 6.5 Wh x 3600 J/(Wh) = 23400 J = 23.4 kJ
Last update: 2/23/12 5:20 PM