When the temperature drops by -3 degrees, there is no need to use the negative sign to indicate the actual meaning.

It means that the temperature of the day is 3 degrees Celsius lower than the original specific temperature.

For example, now it is 15℃, so it is15℃-4℃ =11℃, that is, the temperature has dropped by 4 degrees Celsius. The original temperature was 15℃, which decreased by 4℃, and now it is 1 1℃. Temperature difference refers to the difference of object temperature. According to different averaging methods, it can be divided into arithmetic average temperature difference and logarithmic average temperature difference.

In a period of time, the highest temperature and the lowest temperature are the temperature difference during this period. For example, if the highest temperature in a city is 16℃ and the lowest temperature is -2℃, then its temperature difference is 18℃.

Extended data

The temperature difference between day and night is determined by the difference between the highest temperature during the day and the lowest temperature at night. In actual measurement, the highest temperature during the day is often around 14 in the afternoon, and the lowest temperature at night is often before sunrise.

There are many minerals in seawater, and the specific heat capacity of water is large. Under the same illumination and heat release conditions at night, the temperature change of water is very small, resulting in a small and slow temperature change. The specific heat capacity of mud and sand in inland areas is small. Under the same conditions, the temperature changes greatly, so the temperature changes greatly.

Since 1960s, many thermoelectric generators have been successfully used in space shuttle, military and ocean exploration. With the continuous progress of science and technology, the application fields of thermoelectric generators are gradually expanding, not only in military and high-tech fields, but also in civil fields.

Voyager 1 spacecraft needs 25 years of scientific exploration in space, and all the electric energy on the spacecraft is provided by thermoelectric conversion module. Its power generation system includes 1200 thermoelectric generator, and neutron decay of radioactive fuel Pu-238 provides heat energy. The power system has been running safely for 2 1 year, and it is expected to continue working 15 to 20 years.

References:

Baidu encyclopedia? Temperature difference (high and low temperature difference)