What's the climate like in Xichang? Can you answer me?

Xichang belongs to subtropical monsoon climate (or subtropical plateau monsoon climate), which is characterized by high temperature and rainy summer and mild and little rain in winter. Compared with the plain at the same latitude, it has the characteristics of cool in summer, warm in winter and small annual temperature difference.

Special point

First, it is warm in winter and cool in summer, and the four seasons are like spring.

Xichang is controlled by warm and humid monsoon in southwest and southeast in summer, with concentrated precipitation, not hot in midsummer, and cool and humid in summer and autumn. Affected by the polar continental air mass in winter, the high altitude is controlled by the dry and warm westerly airflow in the south branch, and the winter is very warm, forming the climate characteristics of "no severe cold in winter, no high temperature in spring, no intense heat in summer and cool in early autumn". There are many sunny days, with strong solar radiation during the day, the ground temperature rises sharply, the radiation in the clear sky is lost at night, the temperature drops rapidly, and the temperature difference between day and night is large. There is a saying that "there is no winter and summer in a year, and there are four seasons in a day". The temperature in annual range is small and the daily range is large. The annual average temperature range is only 13C, which is one of the areas with the smallest annual average temperature range in China.

Second, the rainfall is abundant and concentrated.

The rainfall in Xichang is concentrated, and 93% of the annual rainfall is concentrated in the summer half year. Night rain rate is high in rainy season, and the amount of night rain accounts for about 75% of the annual rainfall. During the day, the temperature in the mountainous area around the basin is low and the temperature rises slowly, and the air sinks, which is not conducive to water vapor condensation and less rain. The temperature in the basin rises rapidly in the afternoon, and the air around the basin rises along the hillside at night, which is conducive to the condensation of water vapor, so it is rainy. The Indian Ocean monsoon brings a lot of water vapor and forms unstable air stratification, which is prone to thunderstorms, often at night, and the rain clears up after dawn.

3. Sufficient sunshine and abundant light and heat resources.

Xichang is high in altitude, low in latitude, with large solar altitude angle, many sunny days, many sunshine hours, strong ultraviolet rays, high wind speed, large evaporation of water vapor, low humidity, few foggy days and good visibility. Its sunshine is the high-value center in the same latitude zone, and its accumulated temperature meets the needs of crop growth in four seasons. The ground temperature is higher than the air temperature, and the evaporation is greater than the precipitation. In winter and spring, the weather is crisp, sunny during the day and breezy at night, so it is called "Moon City".

Fourth, the four seasons are not obvious, and the dry and wet seasons are distinct.

Xichang 65438+February-March is the dry season, and June-September is the rainy season. In the dry season, the climate is dry, the temperature is high during the day and afternoon, the daily temperature difference is large, the sunshine time is long, and the ground wind is strong in the afternoon. The rainy season is characterized by concentrated precipitation, abundant rainfall, small daily temperature difference and continuous rain at night. In addition, in this season, air stratification is very unstable, convection is strong, and thunderstorms and hail are frequent. Due to the different monsoon intensity, advance and retreat time, precipitation is unevenly distributed in time and space, and it often suffers from natural disasters such as drought and flood.

Verb (abbreviation of verb) In the transitional season, the climate is changeable.

April-May in Xichang and 10- 1 1 are the seasons of air flow changes in winter and summer, which are called transition seasons. April-May is the transition from dry season to rainy season, which has both dry season climate characteristics and some rainy season climate characteristics. The solar altitude angle is increasing, the atmosphere receives more and more solar radiation, the warm air is gradually strengthened, the cold air is gradually weakened, the cold and warm air alternate frequently, and the weather is changeable. In April, the afternoon wind is still very strong. In May, due to the northward withdrawal of the upper-air jet, the southwest wind weakened obviously in the afternoon, and the upper-air circulation situation is changing to the rainy season. The atmosphere is often unstable, and cloud cover, thunderstorm, hail and rainfall increase. 10- 1 1 is the transition from rainy season to dry season. The basic climatic characteristics in rainy season gradually decrease, while those in dry season gradually increase. The airflow in the south branch is obviously strengthened and expanded southward, the scale of westerly ridge is obviously increased, the intensity of cold air is strengthened, the subtropical high is weakened and moved southward, the summer monsoon is weakened until it disappears, and the water vapor transport is obviously reduced.

Six, the mountain three-dimensional climate is obvious, and the climate types are diverse.

Xichang is located in the plateau, with prominent vertical belt and large height difference. The temperature decreases with the elevation. Every time the altitude rises 100 m, the temperature drops by about 0.6℃, the active accumulated temperature drops by 282℃, and the frost-free period decreases by 12 days. Alpine valleys in China can be roughly divided into six climatic zones according to different mountain slopes: 1200— 1300m is equivalent to tropical climate in South Asia; 1300— 1800 m is in the middle subtropical zone; 1800-2100 meters is north subtropical; 2 100-2500m is the south temperate zone; 2500-3000 meters is the middle temperate zone; Above 3000 meters is the north temperate zone. There is no summer in Luoji Mountain and Yak Peak, and there is no winter along Yalong River. Therefore, the climate of Xichang has three-dimensional climate characteristics: "the top of the mountain is cold, the mountainside is mild, and the valley is dry and hot" and "one mountain is divided into four seasons, and ten miles are different from the sky". The diversity of climate resources is beneficial to crop growth in different climatic zones.

Temperature, accumulated temperature and ground temperature

First, the gas temperature

The average temperature in Xichang is 17.2℃, the highest temperature in August is 23.8℃, and the lowest temperature in October is 9.4℃. The absolute maximum value is 35.0℃, 1927 and 1933 in June, and the absolute minimum value is -2℃, which appears in 1930 and 1935 in June. Generally, the temperature is moderate, and the temperature difference between morning and evening is large, and the temperature difference is often around 10℃. In a year, the temperature in each season is not much different. The average temperature in July is 22.5℃ for many years, and the average temperature in Leng Yue is 9.5℃ in October. The annual temperature is 65438 03.0℃, which is one of the areas with the smallest temperature change in China. The monthly relative temperature ranges from May to June by 0.8%, and from February to March and10-1month by 35. 1% and 28.3% respectively. The temperature rises early and sharply in spring, and drops rapidly in autumn, which is higher than that in autumn. The extreme minimum temperature of -3.8℃ appeared on February 9 1977, and the low temperature intensity was not great. The highest extreme temperature is 36.6℃, appearing on May 3 1983 and 3 1. The daily temperature difference is large, with a monthly average of 14. 1℃, which is 4℃-6℃ higher than that in Sichuan Basin. From late March to September, the average number of days with the highest temperature above 30℃ is 40.3 days, with the highest year 1957 reaching 57 days and the lowest year 1974 only reaching 10 days, with the highest in May being 12 days and only 2.6-6.9 days in other months. The maximum temperature of 35℃ has 23 days in 8 of the 30 years, with an average of 0.76 days in 30 years, all from mid-May to early June, and the longest years are 1954 and 1963, reaching 5 days every year. The lowest temperature occurs from early February of 65438 to late February of the following year, and the number of days is ≤0.0℃, with an average of 5 days in 30 years, 65438+0.8 days in February, 1 2.7 days in February, and 65438+0.6 days in February. The longest years are 1976 and/kloc-.

According to the meteorological climate, the average temperature

Second, the accumulated temperature

The average daily temperature in Xichang is stable, ≥0.0℃, 5.0℃, 10.0℃, 15.0℃. The initial, final and accumulated temperature is ≥ 0.0℃ for 30 years, the average accumulated temperature is 6206.2℃, and the days between the initial and the whole day are 365.3 days, with the highest annual 1952. ≥5.0℃, accumulated temperature 6 148.5℃, starting and ending days 357.2 days, highest year 1952 6539.3℃, lowest year1974 5533.1℃; The accumulated temperature ≥ 10℃ is 5329.9℃, the first day is February 25th, the whole day is165438+1October 29th, and the starting and ending days are 277.6 days.

Sunshine evaporation humidity

First of all, the photos of the day

Xichang has strong solar radiation and abundant sunshine. According to the observation of1951-1990, the annual average sunshine hours are 2432. 1 hour, accounting for 55% of the sunshine hours, the longest one is 2660.5 hours (1980), and the youngest one is 2432 hours. It is 200-500 hours longer than Tengchong and Deqin in the west, 500- 1000 hours longer than Guiyang, Zhijiang, Fuzhou, Changsha, Nanchang and Wenzhou in the east, and 1203 hours longer than Chengdu. The high-value period is half a year in winter (65438+ February to May of the following year), with an average monthly sunshine of more than 200 hours, accounting for 60%-70% of sunshine hours, and the highest is March, with sunshine hours of 26 1.2 hours, accounting for 76% of sunshine hours; The low value period is in the summer half year (June-165438+1October), and the average monthly sunshine hours are between 144- 199 hours, accounting for only about 30%-40% of the available sunshine hours, with the lowest sunshine in June and September.

The total solar radiation value of Xichang is 36.2 kcal per square centimeter/kloc-0, and the physiological radiation value is 64 kcal per square centimeter. The total radiation is 45 kcal more than Chengdu, 13.4 kcal more than Kunming and 37 kcal more than Changsha. The highest in April, 14.7 kcal per square centimeter, and the lowest in February, 65438+8.7 kcal per square centimeter.

Sunshine during the growing period of main crops in Xichang: the grain crops in Da Chun are 1.228 hours (6.7 hours per day), with the highest year being 1.384 hours and the lowest year being 1.954 hours. Equivalent to the total sunshine hours in Chengdu and Leshan throughout the year; The grain crop in Koharu is 1.542 hours, the highest year is 1.726 hours, and the lowest year is 1.339 hours, which is more than the total sunshine of all counties in Sichuan Basin. The growth period of sericulture is longer than that of Ningnan county magistrate 174 hours and Nanchong 1077 hours, especially in May 5- 10/0 when mulberries are in full bloom. Xichang has 53 hours more sunshine than Ningnan and 0/60 hours more sunshine than Nanchong, and the light quality is higher than that of Sichuan Basin. During the growth period of flue-cured tobacco, the sunshine in Xichang from May to September is 40 hours more than that in Huili and 73 hours more than that in Yuxi, Yunnan. Xichang has great potential of light energy, and its utilization rate is very low at present. The utilization rates of rice and corn are only 1.5%, wheat is1.65,438+0%, and rape is only 0.4% (calculated by average yield 1.982). Even if it reaches the highest yield level in Xichang, its light energy utilization rate is only 3.3% for rice, 6.0% for corn, 3.6% for wheat, and 0/0/.5% for rape. At present, the maximum utilization rate of short-term field light energy in China has reached 5%.

Second, steam your hair

Xichang is located in the plateau, with abundant sunshine, high ground temperature and temperature, high wind speed, less precipitation and large evaporation in winter. Measured by the National Meteorological Administration for 27 years, the annual average evaporation is 1.945 mm, while the annual average rainfall is only 1.004.3 mm, with a deficit of 940.7 mm and a deficit rate of 93.66%. Except for the rainy season in June and September, the rainfall is greater than the evaporation, and the evaporation is greater than the rainfall in the other eight months. The evaporation is the largest from March to May, with an average of 239.8-262.5 mm per month, especially in Xichang in early spring.

Third, humidity.

The relative humidity in Xichang is relatively small over the years, and the change is relatively stable, with an average of 61951-1980, with an annual average of 65% at the highest and 58% at the lowest, with an average of 73%-75% in June-1October, and 4 years in 30 years. From February to April, the average value is only 4 1%-46%, which is the low value period of the whole year, and the lowest value is only 32% in four months with four years. The relative humidity is the lowest in March and April, and the humidity is O for two months and three days in 30 years, reaching a very low value. The relative humidity in Qionghai River basin in the east can reach 70%, while that in Yalong River in the west is only 60%.

drip

I. Rain

Xichang is controlled by the southwest monsoon of the Indian Ocean, and the rainfall is concentrated in the summer half year, with the same season of rain and heat and abundant rainfall, which is beneficial to crop growth. However, due to the uneven distribution of rainfall in time and space, droughts in winter and spring and floods in summer and autumn often occur, and rainfall shows a slow downward trend. According to the Republic of China