Air Properties: Temperature and Relative Humidity - Guide from the University of Nebraska-Lincoln describes how to use a simplified psychrometric chart to better understand the relationships between air temperature and relative humidity.
Atmospheric Moisture - Sample chapter from the textbook Meteorology Today by C. Donald Ahrens. (PDF 1.5MB 22 pages)
Calibration of Hygrometers and Hygrothermographs - National Park Service (PDF)
Heat Stress Index Chart - and related links.
How to Rejoin a Separated Thermometer Column - Excerpt from The Weather Station Handbook: An Interagency Guide for Wildland Managers.
Instructions for Using the Sling Psychrometer - Sling psychrometers are the standard for accurately measuring ambient temperature and humidity. Every meteorologist should know how to use one correctly. From Professor Grant W. Petty, University of Wisconsin. (PDF)
ITS-90.com - Resource for the International Temperature Scale of 1990 offers information for metrologists, scientists, calibration engineers, and anyone with an interest in the temperature scale and its realisation.
NIST ITS-90 Thermocouple Database - National Institute of Standards and Technology
Online Meteorology Guide: Relative Humidity - University of Illinois
Relative Humidity Table - Derived From Web-Bulb and Dry-Bulb Temperatures - This table gives the approximate relative humidity directly from the reading of the air temperature (dry bulb) and the wet bulb. It is computed for a pressure of 74.27 cm Hg. Tables for different pressures are available from the National Weather Service Forecast Office in Sacramento, California.
Temp, Humidity & Dew Point ONA - Often needed answers from the newsgroup sci.geo.meteorology, this is a collection of some formulae and texts that reflect on connections of temperature, humidity, and dew point temperature.
Temperature Conversion Table - Use this table to convert temperature readings between Fahrenheit and Celcius.
Temperature World - Collection of temperature-related news, resources, and links includes topics such as earth and environment, sensors and instrumentation, science and technology, organizations and standards, and general interest and thermal fun stuff.
Temperatures.com - Information repository on devices used in temperature measurement provides information on temperature sensors, their technologies, sensor types, applications and uses, calibration, standards, technical reference literature, vendors, and related resources.
Using a Psychrometer to Measure Relative Humidity - National Park Service (PDF)
Wind Chill Temperature Chart - and related links.