The Atlantic Meridional Overturning Circulation is a vicious loop that brings ocean currents from the Gulf Stream north into the Atlantic. This water in turn sends Gulf Stream warm salt water into the cold Atlantic Ocean. Then the water comes back toward the Gulf Stream. Mixing the cold and warm waters combined makes a more dense combination sinking toward the bottom of the ocean. As the ocean current makes its way back toward the Gulf Stream, the waters become saltier and denser. This is a good example of feedback, which is a vicious loop that slows down or increases the ocean’s temperature. There is positive and negative feedback but we will discuss the difference in those features a little later in this research paper (Freedman. n.d.).
Another example of feedback would be water vapor. Water vapor in the atmosphere, within the global warming crisis, can have more volume, because of a warmer environment, more water vapor can be obtained. Water vapor is a greenhouse gas. Water vapor also increases the amount of warming in the atmosphere through its feedback cycle. Elevated power through lapse rate, is sent into space by water vapor, and increased radiation throws off some of the water vapor warming effects. Water vapor will play an important role in climate over the next one hundred years. Regardless, water vapor is an added effect on global warming throughout the atmosphere. Also, when water vapor becomes a source for storm development through the evaporation process, more powerful storms can form producing extreme catastrophes (Dressler, 2019).
Clouds are another example of feedback. They reflect light back into space creating a cooler climate. Clouds soak up infrared radiation, which decreases the amount of energy leaving the atmosphere, similar to greenhouse gas. It is possible that in the future clouds will become negative feedback by the cooling effect of clouds being enhanced through initial warming. However, the main consensus scientists have on clouds, and global warming are that clouds produce a warming effect in the atmosphere. Regardless, when one is in the sun and can see a cumulus cloud come overhead the cooling effect from an albedo process is noted. This process is a welcome relief in the heat of the summer (Dressler, 2019).
Positive feedback is where an initial positive change in the climate gives off a second change, which in turn, magnifies the first change that was recorded. An example of positive feedback would be the ice on Greenland. When ice melts it causes the underlying grass and soil to heat up. In turn, this produces a warming effect across the earth. This positive feedback helps in the current situation across the world in global warming through ice shelf melting. Another example of positive feedback is carbon release. As the permafrost in the Tundra begins to thaw it releases enhanced amounts of carbon from the ice age 650,000 years ago. This release produces a chemical effect and methane is developed and released into the atmosphere. As the release of carbon continues it causes elevated temperature rise and therefore more melting of the polar ice caps (Donev. 2020).
El Nino is positive feedback in that it warms the ocean waters by a few degrees, in turn warming the earth’s atmosphere a few tenths of a degree. The definition of El Nino is the temporary warming of the Pacific Ocean in the region around the equator (Pierce, 2000). This warming produces severe storms in the south, and colder weather across the Midwest, and the Northeast United States. The typical jetstream pattern with El Nino depends on its strength. A normal jetstream pattern will take El Nino across Texas and into Florida. This El Nino jet stream pattern tends to bring severe storms across Texas and Florida in the winter during a typical El Nino season. The fluctuation of the jet stream will sometimes move north into Oklahoma during an El Nino setup, bringing severe storms, and tornado potential. Much more rainfall is developed across Texas in a typical El Nino, developing tremendous rainfall, and severe flash flooding. In a strong El Nino Australia and Indonesia receive severe drought conditions that are not favorable to farming (Pierce, 2000). The effects of El Nino in Dixie Alley is that the position of the jet stream across the Southern United States indicates more frequency of tornadoes in an El Nino year. Dixie Alley is an area that frequents tornadoes in an El Nino season and extends from Arkansas eastward to Florida (Edwards, 2015).
Negative climate feedback is where feedback has an initial negative change and the second change decreases the initial change. An example of negative climate feedback would be La nina. La Nina is a negative force, in that it cools the water near the equator by a few degrees, and a second change is it cools the temperature in the atmosphere by a few tenths of a degree. The temperature change in the atmosphere is significant, in that it is felt all over the world. Therefore, the change in the atmospheric temperature is more significant than the ocean temperature change. This second cooling change in temperature makes La Nina negative feedback (Dressler, 2019).
During La Nina, droughts occur across portions of the south, and the southeast United States. Moisture is surged off to the east of tornado alley and into Dixie Alley. This is where El Nino and La Nina have some distinct similarities in tornado formation. However, tornadoes that form in La Nina years tend to be more violent and sometimes elevated in a number of events for a given day. Take the 2011 and 1974 La Nina tornado seasons as moisture was sheared out of tornado alley eastward into Dixie Alley. Both were extreme in Fujita Scale-Enhanced Fujita Scale tornado intensities and numerous tornado events across Dixie Alley. This indicates positive micro-scale climate feedback occurring within tornado events. When moisture is being sheared east into Dixie Alley and the correct setup of a 993 hectopascal low sets up over Tennessee and tracks northeast these types of severe events can take shape. The moisture is the feedback shearing east and water vapor evaporation to enhance the severe weather is the second positive change. Through moisture, present indicates positive feedback in a microscale event within negative world feedback by La Nina. Is it possible more positive or negative feedback is also located within large negative feedbacks within carbon 13 or 14 in the atmosphere? This is a question that is not answered yet in my research early on in education (NOAA, n.d.).
Looking into positive feedback and negative feedback within a microscale event takes us to severe thunderstorms. Within the cumulonimbus is a fine-tuned machine that develops positive feedback through the latent heat process via warm air surging in on the inflow jet. This, in turn, goes into the latent heat process and enhances the energy situation to fuel the supercell storm. If the Bulk Richardson Number and other parameters are balanced within the storm environment a tornado can form. The rear flank downdraft brings cooler air, mixing with the warm moist air, and eventually, if the mixing is right in the lower levels of the updraft process helps produce the tornado. However, in a negative feedback situation, the rear flank downdraft (RFD) blows out the warm moist air from the inflow jet. The next phase of change is the RFD goes straight through and past the inflow jet changing the storm to an outflow dominant feature. At the time of this occurrence, the winds in an RFD are sometimes 74 to 120 miles per hour. This cool dry air (RFD) blasts through anything in front of it, producing a temperature cooling difference in, and ahead of what is now the gust front or shelf cloud respectively (Adams, 2021).
Warming of the Gulf Stream through the Atlantic Meridional Overturning Circulation feedback cycle helps to increase hurricane potential in the Gulf of Mexico. Take Hurricane Katrina for example from August into September 2005. When Hurricane Katrina hit the Gulf Stream just off the west Florida coast it intensified into a category five hurricane. World climate in 2005 was shifting from positive feedback in El Nino to negative feedback in La Nina. Temperatures in the Gulf of Mexico along the Gulf Stream had warmed through the El Nino phase of this feedback. As Hurricane Katrina approached the next phase of the Gulf Stream south of New Orleans a weakening had taken place from category five to category three. Water temperatures south of New Orleans were cooler than west of the Florida coast in 2005. This is why the hurricane weakened as it came into Louisiana south of New Orleans. Still, the catastrophic events of New Orleans are lower than avg. sea level helped flood the city in apocalyptic proportions. Through these feedback examples, one can understand how climate and weather coexist across the atmosphere, land, and throughout the world’s oceans (Adams, 2021).
References:
NOAA. (n.d.). El Niño and La Niña affect spring tornadoes and hailstorms.
https://www.washingtonpost.com/weather/2020/09/29/global-ocean-layers-warming/
P. 116 p.117 feedback search Dressler college book
J.M.K.C. Donev et al. (2020). Energy Education - Positive climate feedback [Online]. Available: https://energyeducation.ca/encyclopedia/Positive_climate_feedback .
Pierce. (2000). So What is an El Niño, Anyway?.
http://meteora.ucsd.edu/~pierce/elnino/whatis.html
NOAA. (n.d.). El Niño and La Niña affect spring tornadoes and hailstorms.
Adams, W. (2021). Ice Age.