高能潮道中的灰泥层——风暴沉积的记录

1992年8月23—24日，安德鲁飓风经过了美国大巴哈马滩北部的两个典型的鲕沉积地区(catcay和Joulfefscay)．在风暴后7个星期，观察到在风暴中沉积于高能潮道(4m深)中的碳酸盐灰泥纹层已经暴露在水下鲕丘的丘槽中，     

蓝镜头

1828年，一位名叫安德鲁·史密斯的学者命名这头宠然大物为Rhincodon typus.即鲸鲨。鲸鲨在越南宗教信仰中被视为神祇，     

圣安德烈亚斯断层

圣安德烈亚斯断层（San Andreas Fault）,长约1300公里,横跨美国加利福尼亚州西部和南部,以及墨西哥下加利福尼亚州的北部和东部。1895年,加利福尼亚大学地质学教授安德鲁·劳森（Andrew Lawson）发现并命名了圣安德烈亚斯断层。     

The Conservation of Helicity in Hurricane Andrew （1992） and the Formation of the Spiral Rainband

The characteristics of helicity in a hurricane are presented by calculating the MM5 model output in addition to theoretical analysis. It is found that helicity in a hurricane mainly depends on its horizontal component, whose magnitude is about 100 to 1000 times larger than its vertical component. It is also found that helicity is approximately conserved in the hurricane. Since the fluid has the intention to adjust the wind shear to satisfy the conservation of helicity, the horizontal vorticity is even larger than the vertical vorticity, and the three-dimensional vortices slant to the horizontal plane except in the inner eye. There are significant horizontal vortices and inhomogeneous helical flows in the hurricane. The formation of the spiral rainband is discussed by using the law of horizontal helical flows. It is closely related to the horizontal strong vortices and inhomogeneous helical flows.