Temperature and Humidity with Arduino
This device will show air temperature in C and F, and % Humidity on an LCD display. A DHT11 Humidity and Temperature Sensor converts the Real world Parameters of Temp/RH into readable Volts for the Arduino A/D section.
Digital output temperature and humidity sensor DHT11
DHT11 from Aosong is a digital temperature and humidity sensor. A type of composite Sensor that contains a calibrated digital signal output of the temperature and humidity.

"Application of a dedicated digital modules collection technology and the temperature and humidity sensing technology, to ensure that the product has high reliability and excellent long-term stability. The sensor includes a resistive sense of wet components and an NTC temperature measurement devices, and connected with a high-performance 8-bit microcontroller."