Understanding Scientific Units

Earth science data parameters have very specific definitions and units. The links below will access some definitions for science parameter units by the topic of interest.
Temperature | Pressure | Radiation | Aerosols | Air Quality | Clouds | Surface
All Unit Definitions | Full Science Glossary | The Metric System

micrometer or micron:
one-millionth of a meter (10.e-6 or 0.000001 m). Human hair is approximately 100 microns in diameter.  
The Metric System
One billionth of a meter (10.e-9 or 0.000000001 m). There are a billion (1,000,000,000) nanometers in one meter.  
The Metric System