Why is atmospheric pressure low in summer and high in winter?
Category: Science and Engineering
Problem description:
Why is the atmospheric pressure low in summer and high in winter?
Analysis:
The Earth is surrounded by thick air, which is called the atmosphere. Air can flow as freely as water, but it is also affected by gravity. Therefore, there is pressure inside the air in all directions. This pressure is called atmospheric pressure. In 1654, Glick conducted the famous Magdeburg Hemisphere Experiment in Magdeburg, Germany, which gave people a profound understanding of atmospheric pressure, but people still don't know how big the atmospheric pressure is. Eleven years later, Italian scientist Torricelli filled an 80-centimeter-long thin glass tube with mercury and placed it upside down in a water tank filled with mercury. He found that the mercury in the glass tube dropped by about 4 centimeters and then stopped falling. No air enters this 4 cm space, it is a vacuum. Torricelli concluded from this that the pressure of the atmosphere is equal to the length of the mercury column. According to the pressure formula, scientists have accurately calculated that the atmospheric pressure under standard conditions is 1.01 × 105 Pa
1 standard atmospheric pressure = 760 mm of mercury = 76 cm of mercury = 1.013 × 105 Pascal = 10.336 meters of water column.
Standard atmospheric pressure value and its changes
——Zhang Jihuai
The regulations of standard atmospheric pressure value have undergone several changes with the development of science and technology. It was originally specified that the atmospheric pressure at sea level at a temperature of 0°C, a latitude of 45°, and a clear day is the standard atmospheric pressure, which is approximately equivalent to a height of 76 centimeters of mercury. Later, it was discovered that the atmospheric pressure value under this condition is not stable and changes due to the influence of wind, temperature and other conditions. Therefore, the height of 76 centimeters of mercury was specified as the standard atmospheric pressure value. But later it was discovered that the pressure value as high as 76 centimeters of mercury was also unstable. The density of mercury changed due to the influence of temperature; the g value also changed with latitude.