If you are a regular viewer of weather broadcasts, chances are you’ve heard the following from your local TV meteorologist: “plenty of sunshine is in store today as high pressure is in control over the area.” Or: “expect rain to spread into the area as a low pressure system approaches.” It is well established that high pressure is generally associated with nice weather, while low pressure is generally associated with cloudy, rainy, or snowy weather. But have you ever wondered why?
In order to understand the types of weather conditions generally associated with high and low pressure systems, we must think “vertically.” The motion of air in the atmosphere above our heads plays a large part in the weather we experience here at earth’s surface. Basically, air cools as it rises, which can cause water vapor in the air to condense into liquid water droplets, sometimes forming clouds and precipitation. On the other hand, sinking air is associated with warming and drying conditions. So the first important point to keep in mind is rising air = moistening, sinking air = drying.
So what does this have to do with high and low pressure? Well, as you may have guessed, high pressure is associated with sinking air, and low pressure is associated with rising air. But why? The answer has to do with the typical air flow around high and low pressure. Physically, it seems to make sense to have air flow from high pressure to low pressure. For reasons I won’t get into in this post, the airflow (due to the Earth’s rotation and friction) is directed slightly inward toward the low pressure center, and slightly outward away from the high pressure center: …more
Until Voyager reached the outer solar system we knew very little about the planets that inhabited this region of space. What we have discovered over years of exploration has both excited and mystified us. Come explore the science of the outer planets. Learn what we have already discovered, and discover what we have yet to learn.
Feb 28, 2013
A previously unseen ring of radiation formed within the Earth’s Van Allen belt in September of 2012 and then vanished a month later. That is the finding of a team of researchers in the US, which analysed the first data available from the twin spacecraft of NASA’s Van Allen Probes mission. The anomalous ring – made up of high-energy electrons – stayed largely unchanged, until it was disrupted and “virtually annihilated” by a powerful interplanetary shock wave. The new findings show how we need a better understanding of the underlying mechanisms of the Van Allen belts. …more
James Van Allen discovered the radiation belts during the 1958 launch of the first successful U.S. satellite. Subsequent missions have observed parts of the belts, but what causes the dynamic variation in the region has remained something of a mystery. …more
Turning the “hydrogen economy” concept into a reality, even on a small scale, has been a bumpy road, but scientists are developing a novel way to store hydrogen to smooth out the long-awaited transition away from fossil fuels. Their report on a new solid, stable material that can pack in a large amount of hydrogen that can be used as a fuel appears in the ACS journal Chemistry of Materials. …moreJournal reference: Chemistry of Materials Provided by American Chemical Society
New satellite data from Indian’s moon mission Chandrayaan-1 has revealed a good amount of historic tectonic activity on the lunar surface, very similar to that on Earth . Scientists studying geological processes on the lunar surface now report faults and grabens in partially and completely shadowed crater interiors of the lunar polar regions.
Saumitra Mukherjee of the School of Environmental Sciences at Delhi’s Jawaharlal Nehru University along with colleague Priyadarshini Singh investigated data from the microwave sensor (MiniSAR) of the Chandrayan- 1 satellite using the image analysis software ENVI.
“The geological processes on the moon are marked with various tectonic features suggestive of similar geological activity occurring on the Earth,” Mukherjee told Nature India. He said the tectonic activity could have been generated by cosmic rays and solar wind flux variability coupled with some interior tectonic activity and meteorite impacts. …more
Do you feel nervous when you make a credit-card transaction using your mobile phone? Your worries could soon be a thing of the past, thanks to a low-cost device that could bring powerful cryptography to portable devices. That’s the aim of Bruno Sanguinetti and colleagues at the University of Geneva in Switzerland, who have created a quantum random-number generator (QRNG) that uses low-cost electronic components including a mobile-phone camera. …more
If you tune in to the opening ceremony of the World Cup in São Paulo on June 12, you might see something truly spectacular. If things go according to plan, a paralyzed young adult will walk onto the field and kick a soccer ball, assisted by a robotic exoskeleton operated by the person’s brain. …more
ScienceAlert Staff 5/16/14
The spot has been rapidly shrinking over the past two years, and is now at its smallest size ever, NASA has reported.
The famous red storm on Jupiter’s surface was once more than 41,000 kilometres wide, but NASA’s Hubble Space Telescope has recently measured it at less than half that size. …more