Use a deep-fry thermometer to measure the temperature.
These measure the temperature and salinity of the top 2,000 metres of the world's oceans.
Scores of other sensors measure the temperature of the air, soil, bark and tree canopy.
Both Vega spacecraft carried infrared spectrometers designed to measure the temperature of the Halley nucleus.
Oceanographers spent a 40-hour stint throwing hi-tech probes overboard at regular intervals to measure the temperature and saltiness of the ocean.
Instruments on satellites can measure the temperature of the surface water from hundreds and even thousands of miles away in space.
Doug McNeall added, "If you want to measure global warming on timescales of about a decade, measure the temperature of the oceans.
Many people measure the temperature in their garden where a precision of one or two degrees is fine, but an inaccurate pollution sensor could falsely reassure or alarm.
Dave is the type of person who, when he comes to a river, doesn't dip his toe in and measure the temperature.
Each truck has an electronic sensor to measure the temperature of the road surface, which can often be colder than the air.
Airports have been told to tighten health checks, and railway stations have been advised to measure the temperature of every passenger.
