Jupiter's Giant Red Spot
One of the most conspicuous facets of Jupiter, the largest planet of our Solar System, is the Giant Red Spot. First noticed in the 17th Century it is still present more than 300 years later. Modern scientific techniques have revealed that it is a vast storm, spinning like a cyclone. Unlike our weather systems in which all the hurricanes are low-pressure areas, the Red Spot's anticlockwise direction of rotation in the southern hemisphere reveals that it is a high-pressure system with winds inside the Jovian storm reaching speeds of about 270 mph.
With a diameter of 15,400 miles, the Red Spot is the largest known storm in the Solar System. It is almost twice the size of the entire Earth and one-sixth the diameter of Jupiter itself.
The fact that Jupiter is a gaseous planet has almost certainly contributed to the long lifetime of the Red Spot as a solid surface would swiftly dissipate the storm's energy, much as happens when a hurricane makes landfall on the Earth. However, the Red Spot does change its shape, size, and color, sometimes dramatically. Such changes are demonstrated in images of Jupiter obtained by NASA's Hubble Space Telescope.
Our astronomers like to study weather phenomena on other planets such as Jupiter which have simpler climates in order to gain a greater understanding of our own planet's much more complicated climate. Jupiter provides them with weather phenomena under very different conditions than those prevailing on Earth against which their climatic models can be analysed. This knowledge can also be applied to places in the Earth's atmosphere that are over deep oceans, making them more similar to Jupiter's deep atmosphere.
Check out this site for pictures http://www.space.com/scienceastronomy/solarsystem/jupiter_pics_001206.html.
Acknowledgements: Recent Channel 4 (Britain) documentary "Planet Action"