一些常用的单位换算
Length
1 (statute) mile (mi) = 1.6093 kilometer (km)
1 (nautical) mile (mi) = 1.8520 kilometer (km)
1 foot (ft) = 0.3048 meter (m)
1 yard = 0.9144 meter (m)
1 inch (in) = 2.54 centimeter (cm)
1 angstrom (A) = 10-8 centimeter (cm) = 10-10 meter (m)
Area
1 square kilometer (km2) = 106 square meters (m2) = 100 hectares (ha)
1 hectare (ha) = 10,000 square meters (m2)
1 acre (ac) = 4047 square meters (m2) = 0.4047 hectare (ha)
Volume
1 milliliter (ml) = 1 cubic centimeter (cm3)
1 cubic meter (m3) = 1000 liters (L)
1 (US) quart (qt) = 0.9461 liter (L)
1 (US) gallon (gal) = 3.7854 liter (L)
1 (US) pint = 0.4723 liter (L)
1 (US) fluid ounce = 29.6 milliliter (ml)
Mass
1 metric ton (m.t.) = 1000 kilograms (kg)
1 pound (lb) = 0.4535924 kilogram (kg)
1 ounce (oz) = 28.3495 grams (g)
Pressure
1 pascal (Pa) = 1 newton/square meter (N/m2) = 1 Kg m-1 s-2
1 bar = 0.98692 atmosphere (atm) = 105 pascals (Pa)
1 pound per square inch (psi) = 68.97 millibars (mb) = 6897 pascals (Pa)
Energy
1 joule (J) = 1 newton meter (Nm)
1 calorie (cal) = 4.184 joule (J)
1 kilowatt hour (kWh) = 3.6 x 106 joules (J) = 8.60 x 105 calories
Power (energy per unit time)
1 watt (W) = 1 joule per second (J/s) = 14.34 calories per minute (cal/min)
Temperature
from Fahrenheit to Celsius: C = (F - 32) x 5/9
from Celsius to Fahrenheit: F = (C x 9/5) + 32
from Celsius to Kelvin: K = C + 273.15
Radioactivity
1 Curie (Ci) = 3.7x1010 Becquerel (Bq)
1 Gray (Gy) = 1 J/kg tissue = 100 rad
Commonly used prefixes…
| Prefix | Exponent | Example Usage |
|---|---|---|
| peta | 15 | Amount of CO2 in atmosphere (as C): 750 Pg (or Gt) |
| tera | 12 | Pool sizes: amount of water in ocean - 1.37 x 10^9 km³ |
| giga | 9 | Rates: flow of Antarctic Circumpolar Current - 200 x 10^6 m/s |
| mega | 6 | Distance New York - Albany: ~350 km |
| kilo | 3 | Atmospheric pressure: ~1012.5 hPa (=1012.5 mbar) |
| hecto | 2 | Base unit |
| base | 0 | |
| milli | -3 | Typical amount of medicine: ~1 ml |
| micro | -6 | |
| nano | -9 | Wavelength of violet light: ~400 nm |
| pico | -12 | Size of atom: ~10 pm |
| femto | -15 | Detection limit of gas chromatographs for SF6: ~1 fmole/L |
1976标准大气中的大气分层
| 层 | 名称 | 层底位势高度 | 层底几何高度 | 气温递减率 | 层底温度 | 层底气压 | 层底大气密度 |
|---|---|---|---|---|---|---|---|
| 0 | 对流层 | -610 | -611 | +6.5 | +19.0 | 108,900 (1.075 大气压) | 1.2985 |
| 1 | 对流层顶 | 11,000 | 11,019 | 0.0 | −56.5 | 22,632 | 0.3639 |
| 2 | 平流层 | 20,000 | 20,063 | -1.0 | −56.5 | 5474.9 | 0.0880 |
| 3 | 平流层 | 32,000 | 32,162 | -2.8 | −44.5 | 868.02 | 0.0132 |
| 4 | 平流层顶 | 47,000 | 47,350 | 0.0 | -2.5 | 110.91 | 0.0020 |
| 5 | 中间层 | 51,000 | 51,413 | +2.8 | -2.5 | 66.939 | |
| 6 | 中间层 | 71,000 | 71,802 | +2.0 | −58.5 | 3.9564 | |
| 7 | 中间层顶 | 84,852 | 86,000 | — | −86.28 | 0.3734 |
参考：
https://www.ldeo.columbia.edu/~martins/hydro/conversion.htm#Length
https://www.britannica.com/science/atmospheric-pressure