Sometimes you deceive yourself. For example then, when you try to measure the water temperature with a traditional liquid thermometer in the spring. In this way, only the temperature of the surface layer of the water is known, which heats up the fastest.
However, it is still unknown, what temperature is deeper and whether the carps have already started to feed?
To measure the temperature in deeper layers of water, a digital thermometer on a 5-meter cable becomes indispensable. A lead weight with a mass is attached to its sensor 20 g (picture 1). The device prepared in this way can be thrown into the water. The temperature of individual layers of water can be measured with accuracy to 1/10 degree Celsius (picture 2).
Please pay attention to this when buying, that the thermometer cable has at least 3 m in length. My thermometer, purchased in "Metro", it can also be switched to air temperature measurement. Besides, it also shows me the exact time.