This posting to "That Videosite.com" attempts to spoof the British Government's commitment to mitigating climate change, but in a strange turn of events actually does a good job of reminding everyone of the difference between climate and weather, and that an unusually cold day doesn't offset the overall long term trend of climate change, a.k.a. global warming. Why not click the link below and give it a look.
Cheers!
http://www.thatvideosite.com/v/2981/global-warming
Showing posts with label weather. Show all posts
Showing posts with label weather. Show all posts
Thursday, June 20, 2013
Monday, January 14, 2013
Why has it been so cold in the western USA lately?
The western United States experienced an extremely mild, dry winter during 2011-12. This year (2012-13), however, things are different - it's cold, cold, cold! and wetter than last year, too.
For example, where I live in SE Idaho, we have been experiencing low temperatures in the -10 to -20oF range over the last week or so.
Why is it so much colder than last year?
Last year's mild winter can be explained in part by ongoing global warming, but prevailing weather conditions over the Arctic also matter.
There is something called the Arctic Oscillation (AO). The AO has two phases, a positive and a negative phase. During the Positive Phase of AO, low pressure sits over the Arctic and a high pressure system dominates around 45oN. During the Negative phase of AO, the opposite occurs; a high pressure system dominates the Arctic and low pressure exists around 45oN.
You can learn more about it at this site provided by the National Snow and Ice Data Center (http://nsidc.org/arcticmet/patterns/arctic_oscillation.html)
The bottom line is that the AO can switch between its positive and negative phases over a matter of weeks to decades. The dominating phase of AO can have a significant impacts on the weather over the northern hemisphere.
For example, where I live in SE Idaho, we have been experiencing low temperatures in the -10 to -20oF range over the last week or so.
Why is it so much colder than last year?
Last year's mild winter can be explained in part by ongoing global warming, but prevailing weather conditions over the Arctic also matter.
There is something called the Arctic Oscillation (AO). The AO has two phases, a positive and a negative phase. During the Positive Phase of AO, low pressure sits over the Arctic and a high pressure system dominates around 45oN. During the Negative phase of AO, the opposite occurs; a high pressure system dominates the Arctic and low pressure exists around 45oN.
You can learn more about it at this site provided by the National Snow and Ice Data Center (http://nsidc.org/arcticmet/patterns/arctic_oscillation.html)
The bottom line is that the AO can switch between its positive and negative phases over a matter of weeks to decades. The dominating phase of AO can have a significant impacts on the weather over the northern hemisphere.
(Images courtesy of NSIDC.org)
The image above left shows the effects of the "Positive Phase of Arctic Oscillation". During the positive phase (low pressure system over the Arctic) masses of cold Arctic air stay farther north, and the western USA stays warmer and drier than usual. At the same time, coastal Eastern Canada gets colder air than usual. During the Positive phase the North Atlantic storm track can also move farther north than usual, bringing cold, wet winter weather to northern Europe. According to NSIDC.org, we have been experiencing mainly the positive phase of AO since the 1970s.
The image above right shows the effects of the "Negative Phase of Arctic Oscillation." During the negative phase (high pressure over the Arctic), low pressure is much more common around 45oN, and this phase recently developed. During the negative phase colder, wetter air masses than usual are pulled farther south by the low pressure system over western North America. Along with this we normally see the Atlantic storm track pushed farther south, bringing precipitation to the Mediterranean instead of northern Europe.
There are, of course, many other oscillating weather patterns that contribute to conditions we experience, but the AO is one recently switched phases.
Global Warming also plays an important role in generating weather. Even though the Arctic is cold, much more heat than normal is stored there, and it has to go someplace. One thing this does is increase the amount of atmospheric activity and can contribute energy to the polar jet stream, pushing it farther south than usual. The map below shows the jet stream track for 14 January 2013:
The map above shows the jet stream pushing as far south as northern Mexico. My son happens to be there, and he reported recently that they are experiencing freezing temperatures and even snow!
Knowing something about the Arctic Oscillation effects of global warming help us understand weather we experience.
I hope this was helpful.
Friday, March 2, 2012
Climate Change 1: Matter, Energy, Weather, and Climate
If you are like me you know at least a few people who have extremely strong opinions about climate change but don't understanding much about climate science. When someone like this enters into a casual conversation about climate change the discussion can quickly turn into an emotionally charged argument. This, in my experience, is both uncomfortable and unproductive.
In order to understand climate change we don't need opinion, we need an understanding of scientific principles and have access to empirical observations. As I hope you read in my earlier posting "On Science 2: Limitations of Science", science can address only questions that are objective and empirical. This means that an objective question has an actual answer that is not based on personal bias or opinion, and that answer can be discovered via empirical evidence.
My goal in sharing these postings on climate change is to provide you with the background and empirical information (observations) you can use to develop your own scientific understanding of this extremely complex and important part of the natural world. I will do my best to emphasize scientific principles and observations and minimize personal bias as I do so.
OK, let's start with some fundamental scientific principles and some definitions that apply to climate (and lots of other things).
Climate is affected by a large variety of factors, but two of the most important ones relate to matter and energy, so let's start there.
The Law of Conservation of Matter:
This law states that matter cannot be created or destroyed, and that changes in matter affect only the form or chemical condition of the matter involved. This means that if matter goes through any kind of change, that you will end up with the same total amount of matter as you started with. For example, If you weigh something before you burn it, and you add the weight of the ash and gases that are released (yeah, gases have mass) you will discover that the total mass before and after the burning is the same. Plus, if you put something in your garbage can and someone picks up your trash and hauls it away, you do not see the trash any more, but it still exists...someplace.
What does this have to do with climate? Climate, as you will see, is all about the movement of matter and the energy it contains around the planet, and the length of time between when energy enters our planet system (atmosphere, ocean, land) and when it leaves. OK, about energy...
The First and Second Laws of Thermodynamics:
I routinely hear people talking about the weather and think that they are talking about climate and vice versa. Since this is the case I think we should take a little time and think about the difference between climate and weather, as well as how they are related to each other.
In doing this I agree with Jack Handey of Saturday Night Live fame who quipped in one of his Deep Thoughts when he said:
So, what do some experts - The National Oceanic and Atmospheric Administration and The National Snow and Ice Data Center - say about these terms?
Weather:
NOAA defines weather this way:
“Weather is the state of atmosphere-ocean-land conditions (hot/cold, wet/dry, calm/stormy, sunny/cloudy) that exist over relatively short periods like hours or days. Weather includes the passing of a thunderstorm, hurricane, or blizzard, a persistent heat wave, a cold snap, a drought. Weather variability and extreme events may respond unpredictably in response to climate change.” (2)
In order to understand climate change we don't need opinion, we need an understanding of scientific principles and have access to empirical observations. As I hope you read in my earlier posting "On Science 2: Limitations of Science", science can address only questions that are objective and empirical. This means that an objective question has an actual answer that is not based on personal bias or opinion, and that answer can be discovered via empirical evidence.
My goal in sharing these postings on climate change is to provide you with the background and empirical information (observations) you can use to develop your own scientific understanding of this extremely complex and important part of the natural world. I will do my best to emphasize scientific principles and observations and minimize personal bias as I do so.
OK, let's start with some fundamental scientific principles and some definitions that apply to climate (and lots of other things).
Climate is affected by a large variety of factors, but two of the most important ones relate to matter and energy, so let's start there.
The Law of Conservation of Matter:
This law states that matter cannot be created or destroyed, and that changes in matter affect only the form or chemical condition of the matter involved. This means that if matter goes through any kind of change, that you will end up with the same total amount of matter as you started with. For example, If you weigh something before you burn it, and you add the weight of the ash and gases that are released (yeah, gases have mass) you will discover that the total mass before and after the burning is the same. Plus, if you put something in your garbage can and someone picks up your trash and hauls it away, you do not see the trash any more, but it still exists...someplace.
What does this have to do with climate? Climate, as you will see, is all about the movement of matter and the energy it contains around the planet, and the length of time between when energy enters our planet system (atmosphere, ocean, land) and when it leaves. OK, about energy...
The First and Second Laws of Thermodynamics:
(FYI - There is ongoing discussion about whether there are three or four laws of thermodynamics, but I will refer to the two laws that are most applicable to questions about climate.)
The first law of thermodynamics: This law is also known as the law of conservation of energy. It states that there is no change in the total amount of energy in a closed system, even if energy within the system changes from one form to another. This law also states that heat will move from a location higher heat/energy to one of lower heat/energy until the closed system reaches thermal equilibrium.
If, however, you observe an open system, such as our planet which has energy coming and going, then energy will either flow into or out of the system depending on the the energy state of the connected systems, e.g., space, the sun, etc.
What does the first law have to do with climate? For one thing, if Earth became a closed system it would eventually reach a state of thermal equilibrium that would be MUCH colder than we experience today. If this happened, there would be no outside energy to drive things like winds, currents, the water cycle of evaporation and precipitation, photosynthesis, and so one. It would be VERY boring to be a weather forecaster or climatologist, because everything would end up being thermally and climatically static.
If, however, you observe an open system, such as our planet which has energy coming and going, then energy will either flow into or out of the system depending on the the energy state of the connected systems, e.g., space, the sun, etc.
What does the first law have to do with climate? For one thing, if Earth became a closed system it would eventually reach a state of thermal equilibrium that would be MUCH colder than we experience today. If this happened, there would be no outside energy to drive things like winds, currents, the water cycle of evaporation and precipitation, photosynthesis, and so one. It would be VERY boring to be a weather forecaster or climatologist, because everything would end up being thermally and climatically static.
The second law of thermodynamics: This law states that when energy is transformed from one form to another the amount of energy available to do work unavoidably decreases, and the balance of energy is called entropy. Entropy is typically released as low-grade heat. For example, an internal combustion energy runs by burning chemical energy in the form of gasoline. The chemical energy in gasoline is converted into mechanical energy that drives the pistons up and down inside the engine. Not all energy that is released when gasoline burns drives the pistons; the balance of energy (entropy) is released as waste heat that you can feel when you touch the engine block.
What does the second law have to do with climate? The energy to run almost all processes on Earth are driven directly or indirectly by sunlight. Sunlight is extremely high quality energy, but when sunlight is absorbed by something, say the seat of your car, that high quality energy is released as low quality heat (I'll discuss this in a later posting in more detail). This means that we need an ongoing supply of high quality energy to keep the planet running. If we didn't have that, entropy would increase until all energy exists only in extremely low-quality forms, and life as we know it could not exist.
What does the second law have to do with climate? The energy to run almost all processes on Earth are driven directly or indirectly by sunlight. Sunlight is extremely high quality energy, but when sunlight is absorbed by something, say the seat of your car, that high quality energy is released as low quality heat (I'll discuss this in a later posting in more detail). This means that we need an ongoing supply of high quality energy to keep the planet running. If we didn't have that, entropy would increase until all energy exists only in extremely low-quality forms, and life as we know it could not exist.
ON TO OTHER THINGS
Before we go farther with this discussion about climate, we should cover a couple of definitions...
Climate and Weather
Before we go farther with this discussion about climate, we should cover a couple of definitions...
Climate and Weather
I routinely hear people talking about the weather and think that they are talking about climate and vice versa. Since this is the case I think we should take a little time and think about the difference between climate and weather, as well as how they are related to each other.
In doing this I agree with Jack Handey of Saturday Night Live fame who quipped in one of his Deep Thoughts when he said:
"Sometimes I think the so-called experts actually are experts."(1)
So, what do some experts - The National Oceanic and Atmospheric Administration and The National Snow and Ice Data Center - say about these terms?
Weather:
NOAA defines weather this way:
“Weather is the state of atmosphere-ocean-land conditions (hot/cold, wet/dry, calm/stormy, sunny/cloudy) that exist over relatively short periods like hours or days. Weather includes the passing of a thunderstorm, hurricane, or blizzard, a persistent heat wave, a cold snap, a drought. Weather variability and extreme events may respond unpredictably in response to climate change.” (2)
The NSIDC defines weather this way:
“Weather is the day-to-day state of the atmosphere, and its short-term (minutes to weeks) variation. Popularly, weather is thought of as the combination of temperature, humidity, precipitation, cloudiness, visibility, and wind.” (3)
Both of these definitions refer to short-term descriptions of atmospheric conditions that are subject to change locally on a minute-to-minute basis.
Climate:
NOAA defines climate this way:
"Climate is the weather pattern we expect over the period of a month, a season, a decade, or a century. More technically, climate is defined as the weather conditions resulting from the mean, or average, state of the atmosphere-ocean-land system, often described in terms of"climate normals" or average weather conditions. Climate Change is a departure from the expected average weather or climate normals." (4)
The NSIDC defines climate this way:
"Climate is defined as statistical weather information that describes the variation of weather at a given place for a specified interval. In popular usage, it represents the synthesis of weather; more formally it is the weather of a locality averaged over some period (usually 30 years) plus statistics of weather extremes. We talk about climate change in terms of years, decades or even centuries. Scientists study climate to look for trends or cycles of variability (such as the changes in wind patterns, ocean surface temperatures and precipitation over the equatorial Pacific that result in El Niño and La Niña), and also to place cycles or other phenomena into the bigger picture of possible longer term or more permanent climate changes." (5)
These definitions refer to a long-term average (usually at least decades long) of the same atmospheric factors we consider when we refer to weather, and can be used to determine whether there is any deviation from long-term averages. These long term shifts or changes are what we refer to as climate change. In addition, some types of climate change can be observed globally, and others can be observed regionally.
Now that we have covered some basic scientific principles and a few definitions, you are ready to move on to the next topic - an introduction to the physical structure and geologic history of the atmosphere, land, and oceans. This information is also an essential component of the foundation of information you will need to understand data about the climate, but this will have to wait until next time - this posting is already too long.
References:
1. Handey, J. 1994. Deepest Thoughts - So Deep They Squeak. Hyperion Press, NY.
“Weather is the day-to-day state of the atmosphere, and its short-term (minutes to weeks) variation. Popularly, weather is thought of as the combination of temperature, humidity, precipitation, cloudiness, visibility, and wind.” (3)
Both of these definitions refer to short-term descriptions of atmospheric conditions that are subject to change locally on a minute-to-minute basis.
Climate:
NOAA defines climate this way:
"Climate is the weather pattern we expect over the period of a month, a season, a decade, or a century. More technically, climate is defined as the weather conditions resulting from the mean, or average, state of the atmosphere-ocean-land system, often described in terms of"climate normals" or average weather conditions. Climate Change is a departure from the expected average weather or climate normals." (4)
The NSIDC defines climate this way:
"Climate is defined as statistical weather information that describes the variation of weather at a given place for a specified interval. In popular usage, it represents the synthesis of weather; more formally it is the weather of a locality averaged over some period (usually 30 years) plus statistics of weather extremes. We talk about climate change in terms of years, decades or even centuries. Scientists study climate to look for trends or cycles of variability (such as the changes in wind patterns, ocean surface temperatures and precipitation over the equatorial Pacific that result in El Niño and La Niña), and also to place cycles or other phenomena into the bigger picture of possible longer term or more permanent climate changes." (5)
These definitions refer to a long-term average (usually at least decades long) of the same atmospheric factors we consider when we refer to weather, and can be used to determine whether there is any deviation from long-term averages. These long term shifts or changes are what we refer to as climate change. In addition, some types of climate change can be observed globally, and others can be observed regionally.
Now that we have covered some basic scientific principles and a few definitions, you are ready to move on to the next topic - an introduction to the physical structure and geologic history of the atmosphere, land, and oceans. This information is also an essential component of the foundation of information you will need to understand data about the climate, but this will have to wait until next time - this posting is already too long.
References:
1. Handey, J. 1994. Deepest Thoughts - So Deep They Squeak. Hyperion Press, NY.
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