The space environment above the surface of 100 km is not empty. There still part of the Earth's neutral atmosphere and exist charged particles, and it is affected by the Earth's magnetic field, interplanetary magnetic field and solar activity. The variations of phenomenon in the space environment has attracted attention in recent years. As the weather generally varies with time and location as daily weather, scientists call these changes "space weather".
Space weather is mainly affected by solar activities which can be further divided into quiet and active conditions. When the solar activity is quiet, space weather has solar cycle, annual, seasonal and daily variations. However, when the solar activity is under active condition, severe X-ray radiation or high-energy plasma would erupt from the Sun to the space enviroment. The plasma density in the space environment is increased, and the Earth's magnetosphere is squeezed by the solar wind to cause a magnetic storm, which will cause severe space weather events.
Space weather can't be felt in our daily life, but it could directly or indirectly affect the operation of satellites and radio communications. In severe cases, it may cause a signal interruption in high-frequency communication, satellite positioning error or missing data transmission. It would impact artificial satellites, space stations, astronauts, satellite communications, GNSS positioning and radio communications, and damages equipments in space and even ground-based facilities. Therefore, space weather is actually has impacts on human livelihood, communications, military, etc. Therefore, it is necessary to provide real-time space weather information and let the general public know about space weather influence to avoid damges while severe space weather occuring.