The hottest solar term in a year.

The heat is the last solar term in summer. "Summer heat" is heat, and summer heat is extremely hot. The summer heat is the fiercest and hottest solar term in a year, and the "hot and humid steaming" reaches its peak at this time. Climatic characteristics of the great summer heat: high temperature and extreme heat, frequent thunderstorms and typhoons.

Summer is hot because the heat on the earth's surface mainly comes from the sun. Every year from the summer solstice, the sun shines directly on the Tropic of Cancer, and the heat on the earth's surface is the greatest. Secondly, during the hot summer, the time difference between day and night is large, which is 13 hours during the day and 1 1 hour at night, with a time difference of 2 hours.

Because the days are long and the nights are short in summer, the heat gained during the day is more than the heat radiated at night, and the income and expenditure are unbalanced, so the temperature accumulation near the surface will become larger and larger, reaching the maximum during the summer solar term. It is precisely because of the solar altitude angle and heat budget that the summer solar term temperature is the highest.

Meteorological change

China is a typical monsoon climate, which is controlled by subtropical high and other atmospheric circulation systems. From mid-June to mid-July, the main rain belt in eastern China generally extends from South China and Jiangnan to Jianghuai area. Late July ("seven drops and eight liters") is equivalent to the period from the scorching heat to beginning of autumn. With the seasonal northward movement of the subtropical high circulation system, the southwest monsoon will also move northward.

The southwest wind around the subtropical high transports the warm and humid airflow of tropical and subtropical regions to the northern region, where it meets the cold air of mid-latitude in North China and Northeast China, and North China and Northeast China begin to enter the rainy season. Northwest China is the arid area with the least annual precipitation in China, because it lives inland and far from the ocean.