This informative post comes from Hannah Christensen Six clouds you should know about – and what they can reveal about the weather March 23, 2018 at phys.org. Text and images from the article.

You don’t need a supercomputer to predict how the weather above your head is likely to change over the next few hours – this has been known across cultures for millennia. By keeping an eye on the skies above you, and knowing a little about how clouds form, you can predict whether rain is on the way.

And moreover, a little understanding of the physics behind cloud formation highlights the complexity of the atmosphere, and sheds some light on why predicting the weather beyond a few days is such a challenging problem.

So here are six clouds to keep an eye out for, and how they can help you understand the weather.

1. Cumulus

Clouds form when air cools to the dew point, the temperature at which the air can no longer hold all its water vapour. At this temperature, water vapour condenses to form droplets of liquid water, which we observe as a cloud. For this process to happen, we require air to be forced to rise in the atmosphere, or for moist air to come into contact with a cold surface.

On a sunny day, the sun’s radiation heats the land, which in turn heats the air just above it. This warmed air rises by convection and forms Cumulus. These “fair weather” clouds look like cotton wool. If you look at a sky filled with cumulus, you may notice they have flat bases, which all lie at the same level. At this height, air from ground level has cooled to the dew point. Cumulus clouds do not generally rain – you’re in for fine weather.

2. Cumulonimbus

While small Cumulus do not rain, if you notice Cumulus getting larger and extending higher into the atmosphere, it’s a sign that intense rain is on the way. This is common in the summer, with morning Cumulus developing into deep Cumulonimbus (thunderstorm) clouds in the afternoon.

Near the ground, Cumulonimbus are well defined, but higher up they start to look wispy at the edges. This transition indicates that the cloud is no longer made of water droplets, but ice crystals. When gusts of wind blow water droplets outside the cloud, they rapidly evaporate in the drier environment, giving water clouds a very sharp edge. On the other hand, ice crystals carried outside the cloud do not quickly evaporate, giving a wispy appearance.

Cumulonimbus are often flat-topped. Within the Cumulonimbus, warm air rises by convection. In doing so, it gradually cools until it is the same temperature as the surrounding atmosphere. At this level, the air is no longer buoyant so cannot rise further. Instead it spreads out, forming a characteristic anvil shape.

3. Cirrus

Cirrus form very high in the atmosphere. They are wispy, being composed entirely of ice crystals falling through the atmosphere. If Cirrus are carried horizontally by winds moving at different speeds, they take a characteristic hooked shape. Only at very high altitudes or latitudes do Cirrus produce rain at ground level.

But if you notice that Cirrus begins to cover more of the sky, and gets lower and thicker, this is a good indication that a warm front is approaching. In a warm front, a warm and a cold air mass meet. The lighter warm air is forced to rise over the cold air mass, leading to cloud formation. The lowering clouds indicate that the front is drawing near, giving a period of rain in the next 12 hours.

4. Stratus

Stratus is a low continuous cloud sheet covering the sky. Stratus forms by gently rising air, or by a mild wind bringing moist air over a cold land or sea surface. Stratus cloud is thin, so while conditions may feel gloomy, rain is unlikely, and at most will be a light drizzle. Stratus is identical to fog, so if you’ve ever been walking in the mountains on a foggy day, you’ve been walking in the clouds.

5. Lenticular

Our final two cloud types will not help you predict the coming weather, but they do give a glimpse of the extraordinarily complicated motions of the atmosphere. Smooth, lens-shaped Lenticular clouds form as air is blown up and over a mountain range.

Once past the mountain, the air sinks back to its previous level. As it sinks, it warms and the cloud evaporates. But it can overshoot, in which case the air mass bobs back up allowing another Lenticular cloud to form. This can lead to a string of clouds, extending some way beyond the mountain range. The interaction of wind with mountains and other surface features is one of the many details that have to be represented in computer simulators to get accurate predictions of the weather.

6. Kelvin-Helmholtz

And lastly, my personal favourite. The Kelvin-Helmholtzcloud resembles a breaking ocean wave. When air masses at different heights move horizontally with different speeds, the situation becomes unstable. The boundary between the air masses begins to ripple, eventually forming larger waves.

Kelvin-Helmholtz clouds are rare – the only time I spotted one was over Jutland, western Denmark – because we can only see this process taking place in the atmosphere if the lower air mass contains a cloud. The cloud can then trace out the breaking waves, revealing the intricacy of the otherwise invisible motions above our heads.

The Earth’s North magnetic pole has been wandering at 10-year intervals from 1970 to 2020, as seen in this animation from the National Centers for Environmental Information.

This post discusses solar and geologic magnetic pole swapping (not with each other of course) and the implications for humans. First the earth and later on the sun.

What On Earth?

Newsweek chose to report yesterday on earth’s meandering north pole as shown in the cool graphic above. That article (here) aims at sensational possible calamities, including high energy radiation, space particles, ozone depletion and electrical blackouts. A more sober assessment is provided by the conversation Why the Earth’s magnetic poles could be about to swap places – and how it would affect us By Phil Livermore and Jon Mound of U. Leeds.Excerpts below with my bolds.

The Earth’s magnetic field surrounds our planet like an invisible force field – protecting life from harmful solar radiation by deflecting charged particles away. Far from being constant, this field is continuously changing. Indeed, our planet’s history includes at least several hundred global magnetic reversals, where north and south magnetic poles swap places. So when’s the next one happening and how will it affect life on Earth?

During a reversal the magnetic field won’t be zero, but will assume a weaker and more complex form. It may fall to 10% of the present-day strength and have magnetic poles at the equator or even the simultaneous existence of multiple “north” and “south” magnetic poles.

Geomagnetic reversals occur a few times every million years on average. However, the interval between reversals is very irregular and can range up to tens of millions of years.

There can also be temporary and incomplete reversals, known as events and excursions, in which the magnetic poles move away from the geographic poles – perhaps even crossing the equator – before returning back to their original locations. The last full reversal, the Brunhes-Matuyama, occurred around 780,000 years ago. A temporary reversal, the Laschamp event, occurred around 41,000 years ago. It lasted less than 1,000 years with the actual change of polarity lasting around 250 years.

In 2003, the so-called Halloween storm caused local electricity-grid blackouts in Sweden, required the rerouting of flights to avoid communication blackout and radiation risk, and disrupted satellites and communication systems. But this storm was minor in comparison with other storms of the recent past, such as the 1859 Carrington event, which caused aurorae as far south as the Caribbean.

The simple fact that we are “overdue” for a full reversal and the fact that the Earth’s field is currently decreasing at a rate of 5% per century, has led to suggestions that the field may reverse within the next 2,000 years. But pinning down an exact date – at least for now – will be difficult.

Since 2014, Swarm—a trio of satellites from the European Space Agency—has allowed researchers to study changes building at the Earth’s core, where the magnetic field is generated.

Historically, Earth’s North and South magnetic poles have flipped every 200,000 or 300,000 years—except right now, they haven’t flipped successfully for about 780,000 years. But the planet’s magnetic field is at long last showing signs of shifting.

The Earth’s magnetic field is generated within the liquid core of our planet, by the slow churning of molten iron. Like the atmosphere and oceans, the way in which it moves is governed by the laws of physics. We should therefore be able to predict the “weather of the core” by tracking this movement, just like we can predict real weather by looking at the atmosphere and ocean. A reversal can then be likened to a particular type of storm in the core, where the dynamics – and magnetic field – go haywire (at least for a short while), before settling down again.

The difficulties of predicting the weather beyond a few days are widely known, despite us living within and directly observing the atmosphere. Yet predicting the Earth’s core is a far more difficult prospect, principally because it is buried beneath 3,000km of rock such that our observations are scant and indirect. However, we are not completely blind: we know the major composition of the material inside the core and that it is liquid. A global network of ground-based observatories and orbiting satellites also measure how the magnetic field is changing, which gives us insight into how the liquid core is moving.

Solar Pole Swapping Puts Earth to Shame

White lines show the magnetic field emanating from the sun’s surface. NASA

Background:

The sun as a whole also has a “global” magnetic field, oriented more or less north-south. So we can think of the sun as a large N-S magnet, like our Earth, but with smaller variously (but not randomly) oriented and continually evolving mini-magnets distributed over its photosphere (visible surface) and throughout its corona (extended atmosphere).

However, unlike our Earth, the sun’s large scale magnetic field flips over on a regular basis, roughly every 11 years. (Actually, Earth’s flips too, very irregularly. The last time was 780,000 years ago. But that’s another story.) Solar magnetic reversals occur close to solar maximum, when the number of sunspots is near its peak, though it is often a gradual process, taking up to 18 months.

A solar flare (the white patch on the sun), and an erupting prominence reaching into space, are features of our active sun, and place the size of Earth in context. NASA

Paul Cally solar physicist Monash U (here)

About the Current Quiet Sun

Euan Mearns considers the implications at Energy Matters The Death of Sunspot Cycle 24, Huge Snow and Record Cold  Excerpts below with my bolds.

8 meter snow depth in Chamonix in the shadow of Mont Blanc in the French Alps January 2018

It looks like the snow in this drift is ~ 8m deep. And this is in the valley, not in the high basins where the snow fields that feed the glaciers lie. Now it’s obviously far too early to begin to draw any conclusions. But IF we get a run of 3 or 4 winters that dump this much snow, it is not inconceivable for me to imagine Alpine glaciers once again beginning to advance. I’m totally unsure how long it takes for pressure in the glacier source to feed through to advance of the snout.

So what is going on? We’ve been told by climate scientists that snow would become a thing of the past. We’ve also been told that global warming might lead to more snow and less snow. And we’ve been told that warming might even lead to cooling. The competing theory to the CO2 greenhouse is that the Sun has a prominent role in modulating Earth’s climate that was so eloquently described by Phil Chapman in his post earlier this week. This theory simply observes a strong connection between a weak solar wind (that is expressed by low sunspot numbers) and cold, snowy winters in the N hemisphere. Uniquely, most of those who argue for a strong solar influence also acknowledge the overprint of anthropogenic CO2. The IPCC effectively sets the Sun to zero. The Sun is entering a grand solar minimum already christened the Eddy Minimum by the solar physics community.

Figure 2 It is crucial to look at the baseline closely that in 2009 actually touched zero for months on end. This is not normal for the low point of the cycle. Figure 3 shows how cycle 24 was feeble compared with recent cycles. And it looks like it will have a duration of ~10 years (2009-2019) which as the low end of the normal range which is 9 to 14 years with mean of 11 years. Chart adapted from SIDC is dated 1 January 2018.

Mearns provides this summary of his article Cosmic Rays, Magnetic Fields and Climate Change

Cosmic rays are deflected by BOTH the Sun’s and Earth’s magnetic fields and there may also be variations in the incident cosmic ray background. Cosmogenic isotope variations, therefore, do not only record variations in solar activity.

This has two significant implications for me: 1) when I have looked into cosmogenic isotopes in the past I have been perplexed by the fact that in parts you see a wonderful coherence with “climate” (T≠climate) while else where, the relationship breaks down, and 2) my recent focus has been on variations in spectrum from the Sun (which may still be important) but to the extent that the Laschamp event (Earth’s magnetic field) may also be implicated in climate change then the emphasis needs to shift to cosmic rays themselves i.e. what Svensmark has been saying for years.

For readers not familiar with Earth’s magnetic field. It periodically flips but on a time-scale of millions of years. The N pole moves to the S pole and in the process of doing so the magnetic field strength collapses as evidenced by “Figure 7” in Phil’s post. The last time this happened was during the Laschamp event ~ 41,000 years ago. There was a full but short lived reversal, but the Earth’s magnetic field did collapse.

Now here’s the main point. We know that the glacial cycles beat to a 41,000 year rhythm that is the obliquity (tilt) of Earth’s axis. The magnetic field originates in Earth’s liquid mainly iron core. This raises the question, can changes in obliquity affect the geo-dynamo. You have to read what Phil has written closely:

Since we absolutely know (don’t we?) that the interglacial to glacial transitions of the current ice age are caused by Milankovitch forcing, the usual interpretation is that there must be some unknown mechanism by which changes in the orbit of the Earth and/or the tilt of the polar axis affect the geodynamo, triggering the excursions.

For decades to centuries, Earth’s N magnetic pole was pretty well fixed to a point in northern Canada. Not much in the news, but it has recently begun to migrate, quite rapidly.

For a more complete description of solar effects effects on earth’s climate see
The cosmoclimatology theory

Earth’s magnetic field, in blue, shields the planet from the solar wind. NASA

Christelle Lagace-Babim, left, and Elise Lagace walk along Rue Jacques-Cartier Friday, after checking out their home in Gatineau, Que., as significant rainfall continues to cause flooding. (Justin Tang/Canadian Press)

A lot of verbage about global warming/climate change is worse than useless because the parties are using terms whose meaning is vague or equivocal, and thus no meaningful interaction occurs. Alarmists/activists claim climate change is real, man-made, and dangerous (Obama tweet). Skeptics/doubters respond that climate is always changing, has been both warmer and cooler in the past, long before humans did anything.

In addition, climate confusion causes statements like this one recently in the CBC: Gatineau flooding ‘tip of the iceberg,’ climate scientist warns

Swollen rivers and streams have threatened hundreds of homes in the Outaouais thanks to recent heavy rainfall — three times the normal amount since April 1.

University of Ottawa climate scientist Paul Beckwith says that’s due to a changing climate, and says we’re seeing its effects “on a day-to-day basis” in weather patterns.

Beckwith points to an increase in extreme weather events across North America as proof. “We’ve changed the chemistry of the atmosphere and the oceans with our greenhouse gases, so we’re seeing the consequences of this now,” he added. “It’s only the tip of the iceberg, so to speak.”

Such reports mislead people to think of the climate acting like some kind of agent causing the weather to change in ways unfavorable to us. That confuses the relation between climate and weather, as we shall see below.

What is “Weather”?

Fortunately in science things get defined not theoretically but by observations and measurements. In science, weather is defined as the behavior we measure on a daily basis. In fact today’s automated weather equipment monitors the weather constantly. Let us consider an operational definition of weather to be the variables for which data is reported into global databases.

Each National Weather Service has its own additional particulars they track, but the common global definition of weather can be seen in the defined elements from the ECA&D weather data dictionary (European Climate Assessment & Dataset)

Weather Measurement Elements

What is weather: Eight variables are measured globally–Sunshine, Sea Level Pressure, Humidity, Cloud cover, Wind, Precipitation, Snow Depth, Temperature. With multiple measures of some variables, weather datasets consist of 13 common elements.

Sunshine (SS) in units of 0.1 hour. Total daily SS plus measures of hours for intervals during the day.

Sea Level Pressure (PP) in units of 0.1hPa Daily average PP plus measures for specific times and parts of the day.

Humidity (HU) in units of 1% of relative humidity. Daily average HU plus measures for specific times and parts of the day.

Cloud Cover (CC) in oktas (0 being clear sky, 8 being completely overcast). Daily average CC plus measures for specific times and parts of the day.

Wind Direction (DD) in degrees azimuth for the wind source (that is, a southerly wind comes from 180 degrees.) Daily average DD plus measures for different times of day, and the direction of maximum gust.

Wind Speed (FG) in units of 0.1 m/s. Daily average FG plus measures for speeds at different times and parts of the day.

Wind Gust (FX) in units of 0.1m/s.  Daily average FX (24 hourly gusts) plus measures for maximums of different durations. (2 to 15 minutes).

Precipitation Amount (RR) in units of 0.1 mm. Daily total RR plus measures of amounts for intervals during the day.

Maximum Hourly Precipitation (MXR) in units of 0.1 mm. MXR for the day plus measures of amounts for intervals during the day.

Snow Depth (SD) in units of 1 cm. Mean daily SD plus measures of depths for intervals during the day.

Mean Temperature (TG) in units of 0.1C. Daily TG plus measures of various ways of calculating TG.

Minimum Temperature (TN) in units of 0.1C. Daily TN plus measures for different times and parts of the day.

Maximum Temperature (TX) in units of 0.1C. Daily TX plus measures for different times and parts of the day.

What is “Climate”?

Change in Frequency of Frost Days in Europe in the Period 1976-2006

To sort out the confusion between “weather” and “climate”, we can also look at how climate is measured and thereby defined. From the same ECA&D source is a climate indices database which is termed Indices of Extremes.

There is one datafile for each index. Each datafile gives information for all available stations in the ECA&D database. The indices are aggregated over the year, the winter-half (ONDJFM), the summer-half (AMJJAS), winter (DJF), spring (MAM), summer (JJA), autumn (SON) and each of the calendar months.

There are 74 indices grouped into twelve categories corresponding with different aspects of climate change. Some categories come directly from weather elements, while others are derivations.

The 74 indices are statistics built upon weather data, adding patterns of interest to humans. For example, temperature is greatly emphasized by adding various concerns with heat and cold on top of temperature records. Also, a compound category focuses on temperature and precipitation combinations and their favorability to humans.

What is Climate: Categories and Indices

Note that climate is operationally defined as statistical patterns of weather data. Some indices are simply averages of daily weather over long term periods. By convention, a 30-year average is used to define a climate baseline for a location.

Other climate indices are based on value judgments according to human interests. For example, heat and cold include many examples like growing days, good tourism days, heating degree days. In fact, a feature of climate is the imposition of human expectations upon nature, other examples being the sunshine indices Mostly Sunny and Mostly Cloudy days.

Andrew John Herbertson, a British geographer and Professor at Oxford, wrote in a textbook from 1901:

By climate we mean the average weather as ascertained by many years’ observations. Climate also takes into account the extreme weather experienced during that period. Climate is what on an average we may expect, weather is what we actually get.

Mark Twain, who is often credited with that last sentence, actually said:

Climate lasts all the time and weather only a few days.

The point is, weather consists of events occurring in real time, while climate is a statistical artifact. Weather is like a baseball player swinging in the batter’s box, climate is his batting average, RBIs, bases on balls, etc.

What is “Climate Change”?

The usefulness of climate indices is suggested by the last category called compound, where temperature and precipitation patterns are combined. In fact those two factors are sufficient to define distinctive local climate zones..

Based on empirical observations, Köppen (1900) established a climate classification system which uses monthly temperature and precipitation to define boundaries of different climate types around the world. Since its inception, this system has been further developed (e.g. Köppen and Geiger, 1930; Stern et al., 2000) and widely used by geographers and climatologists around the world.

Köppen climate zones as they appear in the 21st Century.

As an example, consider how the island of Hawaii looks with its climate zones indicated:

Note: This image comes from an interactive tool and uses a different color scheme than the global map above.  The table below shows the thresholds by which zones are defined.

Köppen and Climate Change

The focus is on differentiating vegetation regimes, which result primarily from variations in temperature and precipitation over the seasons of the year. Now we have an interesting study that considers shifts in Köppen climate zones over time in order to identify changes in climate as practical and local/regional realities.  The paper is: Using the Köppen classification to quantify climate variation and change: An example for 1901–2010 By Deliang Chen and Hans Weiteng Chen Department of Earth Sciences, University of Gothenburg, Sweden

Hans Chen has built an excellent interactive website (here): The purpose of this website is to share information about the Köppen climate classification, and provide data and high-resolution figures from the paper Chen and Chen, 2013:  For more details on Chen and Chen see the post: Data vs. Models 4: Climates Changing

Summary:  Climate Change Defined

Chen and Chen provide a data-based definition of “climate change”. Climate zones are defined by past temperature and precipitation ranges observed by humans. The weather datasets and climate indices inform us whether or not the patterns in a place are moving outside the norm for that location. Climate change appears as a shift in zonal boundaries so that one place starts to resemble a neighboring zone with a different classification.  The table above shows the defined zones and thresholds.

The Chen and Chen analysis shows that almost half of climates around the world will get a year of weather outside of their normal ranges. Getting a decade of abnormal weather is much rarer. True climate change would be a shift enduring over a 30 year period which has been observed in less than 10% of all climate zones.

Summary: The Myth of “Global” Climate Change

Climate is a term to describe a local or regional pattern of weather. There is a widely accepted system of classifying climates, based largely on distinctive seasonal variations in temperature and precipitation. Depending on how precisely you apply the criteria, there can be from 6 to 13 distinct zones just in South Africa, or 8 to 11 zones only in Hawaii.

Each climate over time experiences shifts toward warming or cooling, and wetter or drier periods. One example: Fully a third of US stations showed cooling since 1950 while the others warmed. It is nonsense to average all of that and call it “Global Warming” because the net is slightly positive. Only in the fevered imaginations of CO2 activists do all of these diverse places move together in a single march toward global warming.

For more on measurements and science see Data, Facts and Information

Footnote:

This post was focused on the distinction between weather and climate, so extreme weather events were not discussed, since by definition such events are weather. Still the quote at the beginning shows that activists are working hard to attribute attention-grabbing events as proof of global warming/climate change.

Mike Hulme wrote a series of articles describing the unsuccessful effort to link extreme weather to climate change and said this:
In recent decades the meaning of climate change in popular western discourse has changed from being a descriptive index of a change in climate (as in ‘evidence that a climatic change has occurred’) to becoming an independent causative agent (as in ‘climate change caused this event to happen’). Rather than being a descriptive outcome of a chain of causal events affecting how weather is generated, climate change has been granted power to change worlds: political and social worlds as much as physical and ecological ones.

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