Wednesday, 13 January 2010


"The greatest enemy will hide in the last place you would ever look."
~~Julius Caesar

Galileo Zooms in on Jupiter's Red Spot Credit: The Galileo Project, JPL, NASA

"One of the most strongly identified characteristics of the GRS is its color. Although this characteristic is the most defining, the reason behind the color has yet to be defined. It is thought that some chemical that is dredged up within the vortex of the storm reacts with the light of the Sun to give the storm its reddish hue, but this has yet to be confirmed. The storm has been observed ranging in color from extremely red to unbelievably pale. Several NASA probes sent into the atmosphere of Jupiter to better understand the chemical composition of the cloud have been ruthlessly ripped apart and crushed within the planets enormous atmospheric pressure with little to no data sent back. The winds within the vortex of the GRS can exceed 400 mph! Hurricane Katrina’s sustained a maximum wind speed of 175 mph. The destructive force within the GRS is unparalleled by anything that we can experience on Earth. The highest clouds of the storm extend eight kilometers higher than the rest of the clouds within the planet’s atmosphere."

I wonder if the reddish hue is brought to the Great Red Spot from the outside and above rather than from below?

"Washington, Jan 15 (ANI): Researchers, using spacecraft observations, have shed new light on the great red spot on Jupiter, showing how the spot which is inaccurately described as a storm is actually far calmer than other parts of the planets atmosphere.

According to a report in Discovery news, numerical modeling of the spot, as well as laboratory experiments trying to reproduce the dynamics of the Great Red Spot indicate that it is quite different than earlier believed.

“The Red Spot is very quiet at its center,” said Jupiter researcher Philip Marcus of the University of California at Berkeley.

In fact, the winds at the center are just 9 or 10 miles per hour, whereas around the perimeter they exceed 200 miles per hour."

This revelation about it being calm at the centre of the Great Red Spot is pretty interesting. The calm at the centre of a storm is something which also corresponds directly with the behaviour of low pressure weather systems here on Earth. We often refer to this calm centre as the "eye of the storm".

"The eye is a region of mostly calm weather found at the center of strong tropical cyclones. The eye of a storm is a roughly circular area and typically 30–65 km (20–40 miles) in diameter. It is surrounded by the eyewall, a ring of towering thunderstorms where the most severe weather of a cyclone occurs.

Eyewalls are typically circular; however, distinctly polygonal shapes ranging from triangles to hexagons occasionally occur."

There is another well-known perpetual anticyclone here on Earth which is notoriously calm at its centre, but then surrounded by a wall of strong currents. It is found at the heart of the Bermuda Triangle and is known as the Sargasso Sea.

Image: The Sargasso Sea is a region of slow-moving ocean currents surrounded by rapidly-moving ocean currents, such as the Gulf Stream to its east. It is located off the coast of Bermuda. In this composite image of night-time city lights, you can see the bigger cities in the brighter areas. Credit: NASA, DOD

"The Sargasso Sea occupies that part of the Atlantic between 20 o to 35 o North Latitude and 30 o to 70 o West Longitude. It is in complete contrast to the ocean around it. Its currents are largely immobile yet surrounded by some of the strongest currents in the world: The Florida, Gulf Stream, Canary, North Equatorial, Antilles, and Caribbean currents. These interlock to separate this sea from the rest of the tempestuous Atlantic, making its indigenous currents largely entropious. Therefore anything that drifts onto any of its surrounding currents eventually ends up in the Sargasso Sea amidst its expansive weed mats of sargassum. Because of the entropious currents, it is unlikely anything would ever drift out. The Sargasso Sea rotates slightly itself and even changes position as its surrounding currents change with weather and temperature patterns during different seasons."

Calm waters are also found sitting within all the major subtropical gyres of the oceans (i.e. North Atlantic, South Atlantic, North Pacific, South Pacific and Indian Oceans). These subtropical gyres are all anticyclonic. The center of a subtropical gyre is a high pressure zone. The Sargasso Sea lies at the centre of the North Atlantic gyre. Circulation around a high pressure system is clockwise in the northern hemisphere and counterclockwise in the southern hemisphere.

The eye at the centre of any cyclone or anticyclone is relatively calm when compared to the activity of the surrounding wall. With both types of vortex, cyclone or anticyclone, the wall has been seen to flow faster than the centre - regardless of whether the centre is percieved as being either a high or low pressure area.

There are five major ocean-wide gyres — the North Atlantic, South Atlantic, North Pacific, South Pacific, and Indian Ocean gyres.

Using the North Atlantic and South Atlantic Ocean gyres as an example, I think that they could be seen as two wheels, and that they are being turned by a force which moves between them at the equator. The North Atlantic rotates in a clockwise direction, while the South Atlantic rotates in a counter-clockwise direction. The upper kilometer of the subtropical gyres is primarily wind driven (Huang and Russell, 1994). It appears as if both gyres are being turned by a force which is moving along the surface of the equator from the East to the West - the same direction which light from the Sun follows on the face of the planet.

Looking for something moving westward near the equator, what we find squeezed between the North and South gyres of the Atlantic, and also assisting them, are the North and South Equatorial Currents. Between these sits the Equatorial Counter-Current, and this moves in the opposite direction to the equatorial currents - eastward.

On either side of the equator, in all ocean basins, there are two west flowing currents: the North and South Equatorial (Figure 8q-1). These currents flow between 3 and 6 kilometers per day and usually extend 100 to 200 meters in depth below the ocean surface. The Equatorial Counter Current, which flows towards the east, is a partial return of water carried westward by the North and South Equatorial currents. In El Niño years, this current intensifies in the Pacific Ocean.

The Sun is seen to move westward across the face of the planet because we are revolving eastward on our axis, which means that light from the Sun is joined by the North and South Equatorial Currents. In turn, these are complemented by trade winds, either side of the Equatorial Counter-Current, which push great volumes of water westward in the equatorial currents, raising the sea level in the West. Because the Earth revolves from West to East, it acts as if it is carrying the Equatorial Counter-Current with it. Quite why that is, simply evades me, for the moment at least.

The Earth's average speed of revolution about the Sun is 29.8 km/s. The Earth is spinning on its axis at a rate of 0.5 km/s. At the equator, the Earth's surface moves 40,000 kilometers in 24 hours. People at Earth's equator are moving at a speed of about 1,600 km/h - about a thousand miles an hour - due to Earth's rotation (that's faster than the speed of sound - 1,192 km/hr!) That speed decreases as you go in either direction toward Earth's poles. If you were standing directly on top of a pole it would take an entire day to spin round once on the spot!

It's the same sort of thing if you were standing at the very core of the Earth. The very centre of our planet is revolving very slowly when compared to the speed witnessed by an observer at the equator. At the core of the Earth it will still take you an entire day to turn around on the spot, but then just compare that to the feeling of acceleration on the Earth's surface. The Earth's atmosphere is known to revolve at the same speed as the surface of the planet. That would mean that the atmosphere is moving even faster than the Earth's surface.

From a stand-point way above the North pole, what you would see is the Earth revolving in a counterclockwise direction. If you were stood at the equator, you would see the Sun rising in the East and setting in the West, but really it is the Earth which is revolving around the Sun. If you were able to observe the Earth from the place of the Sun, you would see the Earth revolve with the left-side of the planet, the west side, continously turning to face fresh onslaught from the Sun's energy.

Because the equator is nearer to the energy of the Sun than the poles, the affects of solar energy at the equator are more intense than at the poles. One might also infer that the point of greatest resistance to the energy of the Sun is also at the equator. Just as the filament in a light bulb must offer resistance to an electric current to produce light and heat, then perhaps the same mechanism of resistance is in place at the interface between the Sun's energy and the atmosphere of Earth. If this is the case, then it shall be seen that the North and South poles are the points of least resistance to the Sun's energy, and they also happen to be the coldest places on the planet.

1 comment:

1102 said...