By combining a hurricane model and coupled ocean-atmosphere general circulation model to investigate the early Pliocene, Emanuel, Brierley and co-author Alexey Fedorov observed how vertical ocean mixing by hurricanes near the equator caused shallow parcels of water to heat up and later resurface in the eastern equatorial Pacific as part of the ocean wind-driven circulation. The researchers conclude from this pattern that frequent hurricanes in the central Pacific likely strengthened the warm pool in the eastern equatorial Pacific, which in turn increased hurricane frequency — an interaction described by Emanuel as a “two-way feedback process.”�The researchers believe that in addition to creating more hurricanes, the intense hurricane activity likely created a permanent El Nino like state in which very warm water in the eastern Pacific near the equator extended to higher latitudes. The El Nino weather pattern, which is caused when warm water replaces cold water in the Pacific, can impact the global climate by intermittently altering atmospheric circulation, temperature and precipitation patterns.The research suggests that Earth’s climate system may have at least two states — the one we currently live in that has relatively few tropical cyclones and relatively cold water, including in the eastern part of the Pacific, and the one during the Pliocene that featured warm sea surface temperatures, permanent El Nino conditions and high tropical cyclone activity.Although the paper does not suggest a direct link with current climate models, Fedorov said it is possible that future global warming could cause Earth to transition into a different equilibrium state that has more hurricanes and permanent El Nino conditions. “So far, there is no evidence in our simulations that this transition is going to occur at least in the next century. However, it’s still possible that the condition can occur in the future.”�Whether our future world is characterized by a mean state that is more El Nino-like remains one of the most important unanswered questions in climate dynamics, according to Matt Huber, a professor in Purdue University’s Department of Earth and Atmospheric Sciences. The Pliocene was a warmer time than now with high carbon dioxide levels. The present study found that hurricanes influenced by weakened atmospheric circulation — possibly related to high levels of carbon dioxide — contributed to very warm temperatures in the Pacific Ocean, which in turn led to more frequent and intense hurricanes. The research indicates that Earth’s climate may have multiple states based on this feedback cycle, meaning that the climate could change qualitatively in response to the effects of global warming.
jafar67 on 04 Jan 15Difference between vapor and gas The term gas refers to a substance that is in its gaseous form or a substance that has a single defined thermodynamic state at room temperature whereas a vapor refers to a substance that is a equilibrium between two phases at room temperature, namely gaseous and liquid phase. All matter on earth exists in any of the three states: solid, liquid or gaseous. 'Gas' refers to a substance in the gaseous state. Gases do not have either shape or volume. However, the term 'vapor' or 'vapour' refers to a substance in equilibrium between two phases, usually liquid and gaseous. Vapor is not a state of matter but is a specific type of gas. Gases are in a gaseous state at room temperature. The molecules in a gas can expand to occupy any available volume as there is very little inter molecular attraction. On the other hand, the molecules of a vapor gain energy and vaporize from a substance which is either a solid or liquid at room temperature. For example, steam is a water vapor that turns into water at room temperature. Oxygen, which is a gas, will still be a gas at room temperature. Gas is a state of matter. Vapor is not, it is constantly in transition. An easy way to distinguish between vapor and gas is that vapor is something that can be seen or smelled or something that settles down on the ground, while one cannot see a gas but can only smell it. However, there are some exceptions to this classification, for example, water vapor. Water vapor cannot be smelt and it does not settle down on the ground.
