What is the insulation principle of greenhouses?

What is the insulation principle of greenhouses?
Greenhouses are agricultural building facilities that use light-transmitting covering materials as all or part of the enclosure structure and have certain environmental control equipment to resist adverse weather conditions and ensure that crops can grow and develop normally. The function of a greenhouse is to create environmental conditions suitable for the growth and development of crops under adverse conditions in the natural environment and to carry out effective production.
Principle of greenhouse insulation
After the solar radiation, which is mainly short-wave radiation, enters the greenhouse through the greenhouse lighting material, it increases the indoor ground temperature and air temperature and converts into long-wave radiation. The long-wave radiation is blocked in the greenhouse by the greenhouse covering material, which forms the accumulation of indoor heat and increases the indoor temperature. This process is called the "greenhouse effect". The greenhouse uses the "greenhouse effect" to create a suitable environment for crop growth in the cold season when crops are not suitable for open-field growth, so as to achieve the purpose of off-season production of crops and increase crop yields.
To put it simply: it is heat absorption and heat preservation. On the one hand, the covering material of the greenhouse can absorb light and heat, and on the other hand, it also has the function of maintaining temperature and preventing heat loss.