Definition
Humidity is the amount of water vapor in the air. Water vapor is the gaseous state of water and is invisible. Humidity indicates the likelihood of precipitation, dew, or fog. Higher humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin.
DHT11 Humidity Temperature Sensor
The DHT11 humidity and temperature sensor measures relative humidity (RH) and temperature. Relative humidity is the ratio of water vapor in air vs. the saturation point of water vapor in air. The saturation point of water vapor in air changes with temperature. Cold air can hold less water vapor before it is saturated, and hot air can hold more water vapor before it is saturated. The formula for relative humidity is as follows:
Relative Humidity = (density of water vapor / density of water vapor at saturation) x 100%
Basically, relative humidity is the amount of water in the air compared to the amount of water that air can hold before condensation occurs. It’s expressed as a percentage. For example, at 100% RH condensation (or rain) occurs, and at 0% RH, the air is completely dry.
Components Used
- DHT11
- Arduino Uno
- Connecting Wires
DHT11 Sensor Pinout
DHT11 Arduino Circuit Diagram
Arduino Code for DHT11 Humidity Temperature Measurement
This code requires DHT11 Library Download From: https://github.com/adafruit/DHT-sensor-library
//Humidity and Temperature Measurement
//www.circuits4you.com
#include <dht.h>
dht DHT;
#define DHT11_PIN 2
void setup(){
Serial.begin(9600);
}
void loop()
{
int chk = DHT.read11(DHT11_PIN);
Serial.print("Temperature = ");
Serial.println(DHT.temperature);
Serial.print("Humidity = ");
Serial.println(DHT.humidity);
delay(1000);
}
DHT11 Humidity Temperature Measurement Result
Open serial monitor and observe the readings. Blowing air on sensor will change the humidity readings.
For more Weather related other parameters measurement see below links