云南地形复杂,纬度跨度达八度,冬春为西南暖流所控制,晴朗少雨,夏秋受印度洋季风的影响,阴雨日多,所以夏季平均温度不高,冬季平均温度不低,年较差小。但亦因海拔高,而辐射强,昼夜温差较大,并且六、七、八三个月的温度异常接近,平均又不太高,所以一般作物的生长期都比外省为长,生长慢发育也慢,形成了高产的有利条件。但遇有阴雨,温度就迅速下降,后期的低温对水稻的结实颇有影响。由于高山低谷互相交错,低处才100米,高处达5000米以上,海拔相对高差常在700—2000米,稻作分布高达2,600米,而且稻种的垂直变化十分显著。地势一般西北高于东南,西北及东 Due to the complicated topography in Yunnan, the latitude span reaches eight degrees. Winter and spring are controlled by the southwest warm current. The rainfall is sunny and less rainy. In the summer and autumn, it is affected by the Indian Ocean monsoon. There are many rainy days. Therefore, the average summer temperature is not high and the average winter temperature is not low. But also due to high altitude and strong radiation, large temperature difference between day and night, and six, seven, eight months temperature anomalies close to the average is not too high, so the general crop growth period than other provinces, slow growth Also slow, forming a favorable condition for high yield. However, in case of overcast and rainy weather, the temperature dropped rapidly and the late low temperature had an impact on the firmness of rice. Due to the alpine valley staggered with each other, the lower reaches of 100 meters, the height of up to 5000 meters above sea level, the relative elevation of 700-2000 meters often, rice distribution up to 2,600 meters, and the vertical changes of rice is very significant. Terrain generally higher than the southeast northwest, northwest and east