The role of baroclinic activity in controlling Earth's albedo in the present and future climates.

Clouds are one of the most influential components of Earth's climate system. Specifically, the midlatitude clouds play a vital role in shaping Earth's albedo. This study investigates the connection between baroclinic activity, which dominates the midlatitude climate, and cloud-albedo and how it relates to Earth's existing hemispheric albedo symmetry. We show that baroclinic activity and cloud-albedo are highly correlated. By using Lagrangian tracking of cyclones and anticyclones and analyzing their individual cloud properties at different vertical levels, we explain why their cloud-albedo increases monotonically with intensity. We find that while for anticyclones, the relation between strength and cloudiness is mostly linear, for cyclones, in which clouds are more prevalent, the relation saturates with strength. Using the cloud-albedo strength relationships and the climatology of baroclinic activity, we demonstrate that the observed hemispheric difference in cloud-albedo is well explained by the difference in the population of cyclones and anticyclones, which counter-balances the difference in clear-sky albedo. Finally, we discuss the robustness of the hemispheric albedo symmetry in the future climate. Seemingly, the symmetry should break, as the northern hemisphere's storm track response differs from that of the southern hemisphere due to Arctic amplification. However, we show that the saturation of the cloud response to storm intensity implies that the increase in the skewness of the southern hemisphere storm distribution toward strong storms will decrease future cloud-albedo in the southern hemisphere. This complex response explains how albedo symmetry might persist even with the predicted asymmetric hemispheric change in baroclinicity under climate change.

Experimental study of muscle permeability under various loading conditions.

The permeability of a few muscle tissues under various loading conditions is characterized. To this end, we develop an experimental apparatus for permeability measurements which is based on the falling head method. We also design a dedicated sample holder which directs the flow through the tissue and simultaneously enables to pre-compress it. Although outside of the scope of this work, we recall that the permeability of the muscle has a crucial role in the pathophysiology of various diseases such as the compartment syndrome. Following the measurements of porcine, beef, chicken and lamb samples, we find that the permeability decreases with the pre-compression of the tissue. Similar decrease is observed following dehydration of the tissue. Remarkably, we find that within a physiological pressure range the permeabilities of the various samples are quite similar. This suggests that the muscle permeability is governed by a common micro-mechanical mechanism in which the blood propagates through the interstitial spaces. Under physiological loading conditions, the muscle permeability is in the range between 80 and 230 [Formula: see text].