相关实验视频
Updated: Jan 21, 2026

08:35
Lipid Bilayer Vesicle Generation Using Microfluidic Jetting
Published on: February 21, 2014
15.4K
在过去的40年中,北大西洋上层喷流的剪切增加
Simon H Lee1, Paul D Williams2, Thomas H A Frame1
1Department of Meteorology, University of Reading, Reading, UK.
Nature
|August 9, 2019
概括
气候变化正在增加北大西洋喷流的垂直风力切割, 而不是它的速度. 这种增强的剪切可能会加剧清的空气,影响跨大西洋航班.
科学领域:
- 大气科学
- 气候科学
- 天气学
背景情况:
- 从赤道到极点的温度梯度通过热风平衡推动喷流.
- 气候变化对上层和下层大气温度梯度产生不同的影响,对喷流速度产生相互竞争的影响.
- 之前的研究集中在喷流速度上,
研究的目的:
- 调查北大西洋极地喷流的垂直风切变.
- 确定气候变化是否会影响风速之外的喷流动力.
- 评估变化的喷流特性对航空业的影响.
主要方法:
- 分析北大西洋喷流的区域风速和垂直剪切.
- 使用了三个不同的大气再分析数据集,涵盖了卫星时代 (自1979年以来).
- 研究了温度梯度和风剪趋势之间的关系.
主要成果:
- 北大西洋喷流的区域风速自1979年以来一直保持稳定.
- 在同一时期,垂直风切削增加了15% (范围为11-17%).
- 这种剪切的增加与热风对增强的上层午线温度梯度的反应有关.
结论:
- 气候变化对北大西洋喷流的影响可能被低估,
- 增加的垂直剪切与预计的清空流的加剧一致.
- 增加的流给航空业带来了风险,特别是在跨大西洋航道上.
相关概念视频
Stream Function
2.0K
In two-dimensional incompressible fluid flow, the continuity equation is essential for ensuring mass conservation, meaning that any change in fluid entering or exiting a region is balanced by a corresponding change elsewhere. For incompressible flow, where density remains constant, this requirement simplifies to the condition that the divergence of the velocity field must be zero. Mathematically, this is expressed as,
2.0K
Free Jet
554
Free jets describe the flow of liquid exiting a reservoir through an opening into the atmosphere without resistance. The velocity (v) of the liquid jet is derived using Bernoulli's principle and expressed as:
554
Shearing Stress
1.9K
Shearing stress, denoted by the Greek letter tau (τ), is stress caused by forces acting transversely on an object. These forces create internal ones within the entity in the plane where the external forces are applied. The resultant of these internal forces is the shear in the section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
1.9K
Shearing Strain
1.3K
The shearing strain represents a cubic element's angular change when subjected to shearing stress. This type of stress can transform a cube into an oblique parallelepiped without influencing normal strains. The cubic element experiences a significant transformation when exposed solely to shearing stress. Its shape alters from a perfect cube into a rhomboid, clearly demonstrating the effect of shearing strain. The degree of this strain is considered positive if it reduces the angle between the...
1.3K
Shear Diagram
1.6K
In the study of beam mechanics, shear diagrams play a crucial role in understanding the distribution of shear forces along the length of a beam. Consider a beam AB that is supported at both ends and subjected to perpendicular loads.
First, a free-body diagram of the beam is drawn, representing all the external forces and internal reactions acting on the beam. One can calculate the reaction forces at each support by employing the equilibrium equations of force and moment. The vertical component...
First, a free-body diagram of the beam is drawn, representing all the external forces and internal reactions acting on the beam. One can calculate the reaction forces at each support by employing the equilibrium equations of force and moment. The vertical component...
1.6K
Steady Flow of a Fluid Stream
683
Consider a control volume, such as a pipe with solid boundaries, through which fluid flows and changes direction due to the impulse exerted by the resulting force from the pipe walls. In steady flow, the mass of fluid entering the control volume at a given time, t, with velocity v1, is equal to the mass leaving after infinitesimal time dt, with velocity v2.
During this process, the momentum of the fluid within the control volume remains constant over the time interval dt. By applying the...
During this process, the momentum of the fluid within the control volume remains constant over the time interval dt. By applying the...
683

