The effect of the cold frame

Cold frame has reduced wind speed, stable air flow, increase the barrier in front of the sun radiation, reduce the thermal radiation of strip surface soil, increase the strip temperature and ground temperature etc, and can reduce the evaporation of soil moisture, make the strip temperature climate, due to careless with wooden frame, frame and cover, can absorb a large number of too hot during the day to raise the temperature, the night under the strip frame, covering the closely guarded , slow radiation, therefore, can be durable heat preservation and cold protection. The microclimate of the positive patch changes with the change of the external climate, and the temperature distribution of each local patch is also different. [1] Seasonal variation of temperature in winter and spring, the temperature of the cold frame was higher than that of the open plot, and varied with the seasons. Winter soil can only be cold - resistant vegetables progress overwintering. as the weather gets warmer, the remperature in the cold frame also increases, can progress the seeding and cultivation of warm vegetables. 2/ because the temperature difference between day and night in the furrow is the main heat source is solar radiation, the heat source at night is cut off, the durrow depends on the heat absirbed during the day gradually diffusing outward and cooling, forming a temperature difference between day and night. In addition, due to the limitations of the positive plot equipment, there are seasonal temperature changes in the positive plot. Generally, the temperature difference is about 20℃. The colder the weather is, the greater the temperature difference between day and night [3] The influence of weather changes on the cold frame. The changes of weather, such as sunny, cloudy, wind and snow, also directly affect the temperature rise and fall. The temperature of sunny days can increase several degrees than that of cloudy and snowy days. But in case of continuous cloudy snow, there is no heat source, can make the temperature below zero. Therefore, if the furrow temperature is too low, must strengthen the cold insulation measures. [4] the temperature distribution of various parts of the plot: general south and both sides of the frame temperature is low, near the north and the middle of the temperature is higher, in early spring in the positive plot seedling, easy to cause uneven seedling growth, north and south is wavy, the thing is parabolic, therefore, in the management should pay attention to the inhibition.