The geographical environment of Huangpu District

Huangpu District has a subtropical monsoon climate with abundant heat sources, long frost-free period and abundant rainfall.

Rizhao Huangpu District is located south of the Tropic of Cancer, with a low latitude and a large solar radiation angle. The annual solar radiation heat is 106.7 kcal/cm2, the annual average sunshine hours are 1906 hours, and the sunshine rate is 43 %, rich in heat resources, which is beneficial to the growth of tropical and subtropical agricultural and forestry crops.

Temperature: This area has the characteristics of long summers and short winters, warm all year round with occasional cold spells, a long frost-free period, and suitable for farming all year round. The annual average temperature is 21°C, the coldest month, January, has an average of 13.3°C, and the hottest month, July, has an average of 28.4°C. The interannual temperature changes are very little, and the annual temperature range is 15.1°C. The daily average is ≥10°C. The accumulated temperature is 7599.3℃, and the duration is 350 days. If the climatic average temperature is ≤10℃, it is winter, and if it is greater than 22℃, it is summer. The summer in Huangpu area lasts for 194 days (from April 15 to October 25), and the number of days is less than 10℃. There are more than 40 days per year. In winter, strong cold waves moving southward will cause rapid cooling and low-temperature frost weather. There are 2 to 8 days a year with temperatures below 5°C, and the extreme minimum temperature can reach 0°C. Typical subtropical crops should pay attention to cold protection. Although the temperature is higher in summer, because it is located at the mouth of the Pearl River and regulated by the sea breeze, there is no intense heat.

The annual rainfall in the region is 1,694 millimeters, mainly concentrated from April to September. These six months account for 82% of the annual rainfall. April to June is the pre-flood season, which is mainly frontal rain; July to September is the post-flood season, which is mainly convective rainfall and typhoon rain. The rainy season is defined as daily rainfall ≥30 mm, and the rainy season lasts for 200 days. The rainfall is abundant and the rain and heat are at the same time, which is very beneficial to the growth of crops that like rice, sugarcane and other crops that love temperature and require large amounts of water. The annual rainfall in each season is: summer rain accounts for 45% to 50% of rainfall, spring rain accounts for 26% to ?34%, autumn rain accounts for 16% to 20%, and winter rain accounts for 5% to 8%. The dry season lasts for four months (October to January). Interannual changes in rainfall and uneven seasonal distribution of rainfall cause summer floods and spring and autumn droughts.