A Climate Definition
So when you think about climate what comes to your mind? Does the change in day to day weather seem like climate to you, or does the season to season change seem like climate, well both answers are not wrong, however there is more to the puzzle, a good way to look at climate is to see the entire process. Climate is the look at data from the past 30 years, however my personal belief is that we need to look at 60 years of data, the reason I think that is so that we can seemore variables take place, such as multiple solar cycles, warm and cold PDO phases, warm and cold Atlantic phases along with the ENSO cycles.
Why do I think that is important? My first and simple answer is that each of those items mentioned above have a different outcome on climate, also mixing and matching those variables together will have different outcomes, so if we take a look at 60years this will give us the chance to see these multiple outcomes.
To start with let’s take a look at global features and what that means, first global means that these events are going to occur on a large scale and have global impacts, secondly they will be centralized epicenters, with global impacts.
So our first global feature we will take a look at is the Pacific Ocean, here in the Pacific Ocean we see a really neat feature that takes place, what happens is imagine being in a bathtub, you see how the water splashes from side to side, the Pacific Ocean does the same thing, water travels from Japan to the US and back, via ocean currents. Now during a warm pacific phase, the ocean temperatures through a good portion of the Pacific Ocean are warm and above average, all of this warm water begins to impact the United States via the jet stream. The warmer waters allow for more convection over the oceans, meaning rainfall, snowfall patterns will increase, based on the air temperatures and the season. So usually when the Pacific is in its warm phase we see significant precipitation makers, but don’t confuse this with El-Nino, which we will talk about later. Now, imagine that all the sudden that water went from hot to cold, when this happens we now say that our Pacific Ocean is in the cold phase, during the cold phase we see less moisture being taken from the waters as the water is colder not allowing for all that convection to take place, also along with this drier weather comes colder temperatures. This Pacific Ocean cycle happens roughly on a 30 year pattern and as of 2014 we just recently have entered the colder Pacific Ocean phase. This phase is so important to the United States because the majority of the weather in the United States arrives via the Pacific Ocean.
Next, feature to talk about is the Atlantic Ocean, this also runs a bathtub effect meaning that you will have cold and warm periods. This ocean circulation pattern has impacts on the United States, via our Nor’Easter patterns, along with tropical activity. This ocean pattern has larger impact on Europe though. So let’s examine how a warm phase of the Atlantic Ocean could impact the United States weather patterns, first we will look at Nor’Easters that move up the Eastern seaboard, during a warm ocean phase the waters are warmer allowing for more moisture to be lifted into the atmosphere creating larger precipitation events, however that don’t always mean more snow, because for that we need to examine the depth of the cold air arriving in behind the storm, this just allows the storm to have a higher moisture content.
Now, looking at the tropics, we see that the warmer waters of the Atlantic help to feed tropical systems, this allows the tropical systems to be larger and also stronger, due to the increase availability of rising moisture and increased heat. So if we take a look at when the Atlantic flips into its cold phase, we can see that now we will have a decrease in moisture being picked up and also a cooler atmosphere over the region, both of these parameters will aid in decreasing tropical strength and also decrease the potential moisture for Nor’Easter systems. Like, the Pacific Ocean, the Atlantic Ocean also goes through this phase roughly every 30 years.
The third feature that we will look at is the Arctic Oscillation, this oscillation also has large impacts on weather across the United States, first of all when this Oscillation is in its cold phase, we tend to see stronger amounts of cold air build up in the region, this can then
The Arctic, Pacific and Atlantic circulation patterns are all large scale events that take time to shift back and forth, hence whey they are an important feature to climate study in my thoughts.
Now, those same three circulations we just talked about are associated with surface features as well, the Pacific Circulation pattern is tied into the Pacific High, while the Arctic Oscillation is tied into the Polar High, and the Atlantic Oscillation is tied into the Bermuda-Azores High. Here is a quick background on each of these high pressure centers.
The Pacific High pressure center is located in the Pacific Ocean and causes the ocean currents in the Pacific to flow as they do, with the warm waters flowing up along the coast of Japan and then turning towards the east and flowing eastward in the Northern Pacific, then turning southward with cool waters along the West Coast of the US. This setup is key to understanding climate as it impacts several areas from Tokyo Japan having milder winters to San Diego California having cooler summers near the beaches.
Now, some basic info on the Arctic region, the Polar high travels towards Northern Canada in the winter, bringing cooler weather towards the United States during the winter months, while in the summer it migrates towards the other side of the pole near Russia. This is also a key climate control in that is why for the most part Russia has cool summers especially in the northern parts, while the Northern United States has colder winters.
Lastly, the Atlantic region has the Bermuda-Azores high, during the summer the high migrates towards the United States, near Bermuda, while in the winter it migrates towards the Azores and Europe. This also supports an ocean circulation around it, that is why we see warmer waters along the Eastern United States and cooler waters along Western Europe, hence why the Eastern US along the coast has milder winters, while London as cooler rainy weather.
Now, that we understand these circulations and how they impact the climate, later in the book I will introduce these circulations again when I start talking about Ice-Age and Warming periods of the globe.