My Science School

67% is the percentage of Earth’s surface covered by clouds at any given time. Cloud cover is especially dominant over the oceans where less than 10 per cent of the sky is completely cloud free at any one time. On average 30 per cent of land surface is cloud free. NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) map shows cloud free areas appearing dark blue; module cloud cover appearing light blue; and frequently overcast areas are white.

The cloud band near the equator is caused by large scale atmospheric circulation patterns known as Hadley cells which dominate the tropics.

Hadley cells are atmospheric circulations defined by the convergence of winds containing warm moist tropical air near the equator which rises to altitudes of 10 to 15 kilometres and moves pole wards to about 30 degrees latitude north and south of the equator.

As this warm, moist air rises and cools at higher altitudes, it loses its capacity to hold water vapour which condenses into clouds producing regular thunderstorms.

The cold dry air then sinks back to the surface at about 30 degrees latitude.

Clouds also commonly form in the middle latitudes 60 degrees north and south of the equator where polar and mid-latitude Ferrel circulation cells collide, which pushes air upwards, fuelling the formation of large-scale frontal systems that dominate weather patterns.

Ferrel cells are an atmospheric eddy formed by the upward movement of polar air currents at about 60 degrees latitude and the downward flow of cool dry air from the Hadley cycle at about 30 degrees latitude.

 

Picture Credit : Google

A new robot created by the Massachusetts Institute of Technology and the Technische Universitat Munchen in Germany, can fold itself up, move on its own and, if needed, self-destruct. Measuring 1.7 cms in length and weighing 0.3 gms, it has a neodymium magnet with layers of polystyrene and PVC. If the robot’s materials are heated, it can transform itself into other shapes, hence the “origami” part of its name. A magnetic field made of four special coils powers its movements. It can be commanded to walk, swim or roll and can be made to self-destruct. It could potentially be used for medical procedures, wherein a smaller version would be inserted into the patient’s bloodstream, and would navigate to the area of operation. After operating on the patient, it would be made to self-destruct by dissolving in the patient’s stomach. Another possible use is planetary exploration. Various sizes and models of the robot could collect soil or rock samples, and fit through tiny openings to study objects that are otherwise impossible to reach.

 

Picture Credit : Google

Images taken by the European Space orbiter show what look like hints of blue, liquid in the Arabia Terra region of Mars’ surface. According to the ESA, these blue areas are dark sediments that have built up over time. On the red planet, winds can hit 100 km/h; as these winds travel they erode and gradually wear away the planet’s surface features over millions of years. They also cause sediment build-up, carrying dark, volcanic, basalt-rich deposits across the planet that gets trapped in the craters pockmarking the landscape. Over time, enough of the darker dust collects on the crater’s surface and appears as these blue patches.

 

Picture Credit : Google

Whether you prefer drinking tea or coffee may come down to your genes.

University of Queensland researchers studied the relationship between taste receptor genes and tea and coffee consumption in over 430,000 men and women. People taste bitter flavours like caffeine, quinine and an artificial substance called propylthiouracil differently according to the types of taste receptor genes they have.

Participants with gene variants that made them taste caffeine more strongly were 20 percent more likely than the average person to be heavy coffee drinkers. These caffeine super-tasters were less likely to drink tea as people who are better at detecting caffeine are more prone to becoming addicted to its stimulant effects, and coffee contains more caffeine than tea.

Participants with gene variants that made them more sensitive to the tastes of quinine and propylthiouracil were 4 and 9 per cent more likely than the average person to be heavy tea drinkers respectively. They were also less likely to drink coffee. This may be because super-tasters of quinine and propylthiouracil – both more bitter than caffeine – are more sensitive to bitter tastes overall. They may find the intense bitterness of coffee overwhelming and prefer the gentler bitterness of tea.

 

Picture Credit : Google