What Is a Trunk Line?
The horizontal dew point in the lower atmosphere has a significantly larger but non-frontal narrow strip, also known as the dew point front.
- Chinese name
- Main line
- Foreign name
- dryline
- Related terms
- Dry tongue
- Subject branch
- Meteorology
- The horizontal dew point in the lower atmosphere has a significantly larger but non-frontal narrow strip, also known as the dew point front.
Trunk description
- The main line originally referred to the ground boundary between the warm and humid air westward from the Gulf of Mexico and the hot and dry air from the southwestern desert region, so it was marked by a significant dew point temperature gradient. Later, the ground boundaries of different types of air masses forming dew point fronts in different regions were considered to be trunk lines. [1] During the summer rainstorm in China, the warm and humid air in the south and the dry and cold air in the north meet to form a distinct discontinuity in humidity, which appears as a dew point front in the mesoscale field. Compared with the US main line, the dew point front of China All the difference, the former often causes precipitation and weather, while the latter causes precipitation, often accompanied by larger storms or tornadoes. [2]
Main characteristics
- The main line is a discontinuous line with a large humidity in the horizontal direction. Crossing the main line, the ground level dew point can reach more than 5 ° C per kilometer. In the afternoon, the dew point temperature can vary by 15 ° C within 2 kilometers across the main line.
- The main line is a source of disturbance to the occurrence of convective activities. Cumulus belts often appear in main areas. Cumulus belts can develop into strong thunderstorms. Thunderstorms leave the main line and spread, and then new cumulus belts can develop around the main line.
- The main line promotes the development of convective activities. The two sides of the main line are warm and dry air and cold and wet air. The cold and wet air is usually covered by inverse temperature (commonly called "cap" inverse temperature or dry and warm cover). This inverse temperature stores and accumulates potential energy instability, which can trigger the development of convection.
Trunk formation
- The formation and development of the main line are related to many factors, such as weather scale form, underlying surface characteristics, turbulent mixing, and sky conditions. [1] After the weather-scale low-pressure trough, sinking airflow is usually prevailing, which can form a sinking inversion temperature, forming a dry and warm cover, and finally intersects the ground to form a ground trunk line.