1. Weather Stations: Weather stations around the world measure temperature using thermometers placed in standard shelters that protect them from direct sunlight and other factors that could affect the reading. These thermometers are calibrated and regularly checked for accuracy.
2. Satellites: Satellites equipped with instruments such as radiometers and infrared sensors can measure the temperature of the Earth's surface, atmosphere, and oceans from space. These sensors detect thermal radiation emitted by the Earth, which can be used to calculate temperature.
3. Buoys: Buoys equipped with temperature sensors can be deployed in oceans and lakes to measure water temperatures. These buoys transmit data back to shore stations or via satellites.
4. Data Analysis: Scientists collect and analyze data from weather stations, satellites, buoys, and other sources to create global temperature datasets. These datasets are carefully processed to account for factors such as changes in measurement techniques, instrument biases, and environmental conditions.
5. Climate Models: Climate models are computer simulations of the Earth's climate system. These models incorporate data on temperature measurements, atmospheric conditions, ocean currents, and other factors to simulate past, present, and future climate conditions.
By combining data from various sources and using sophisticated data analysis techniques, scientists estimate global temperatures and identify long-term trends, such as global warming or cooling.
