How Jet Streams Affect Weather

by Rosemary Tayler, 2019 Celestial Planting Calendar

Jet streams are narrow areas of very fast moving westerly (flowing from west to east) winds in the upper levels of Earth’s atmosphere.  They can be thousands of kilometers long and over a hundred kilometers wide, but they are only a few kilometers deep.  These upper atmosphere ribbons of wind have a tendency to push weather systems around the world.  In the Northern Hemisphere, jet streams occur where a warmer air mass to the south meets a colder air mass to the north.  In the Southern Hemisphere, it is the reverse—warmer air in the north meets colder air in the south.  

These boundaries between air masses with significant differences in temperature are the pathways where the jet streams form.  In the fall and winter, the jet stream in the Northern Hemisphere moves further south, allowing the colder air to reach more southerly latitudes. In the spring and summer, it retreats, allowing the heat from the tropics to move further north. 

Jet streams are due to two influences: the heating of Earth’s atmosphere by the Sun and the rotation of Earth on its axis.  When two air masses of different temperatures meet, a difference in air pressure results at this transition zone.  But because of the Earth’s rotation, the wind does not flow immediately from hot to cold; instead the wind is deflected and flows along the boundary of the two air masses.  Because the Earth rotates counterclockwise, the northern hemisphere winds move from west to east.

The strongest jet stream is the polar jet stream, which is 7 to 12 kilometers (4.3 to 7.5 miles) above the ground.  The northern hemisphere polar jet flows over the middle to northern latitudes of North America, Europe and Asia and the oceans between these land masses.  The sub-tropical jet stream occurs at a slightly higher altitude and it is weaker than the polar jet stream. Canada is often influenced by the polar jet stream.  While the winds up there move at a speed of 100 to 160 kilometers per hour (km/h) (62 to 100 miles per hour), they can move as fast as 400 km/h (250 m/h) when there is a large temperature difference between the warm and cold air masses. 

Land masses, particularly mountains, tend to slow down the flow of the jet stream.  This slowing process creates a tendency for the air stream to move in a zigzig or meandering pattern.  The meanders move more slowly than the rest of the air mass and this results an a slowing down of the weather systems at the Earth’s surface.  

Low pressure systems are formed by rising warm air coming into close contact with large masses of adjacent cold air.  During the fall and winter seasons, the sun moves lower in the sky and the land becomes cooler than adjacent bodies of water.  As water retains its heat much longer than the land, areas such as those around Hudson’s Bay and the Great Lakes tend to develop low pressure systems. These low pressure systems are perpetuated by jet streams because they depend on a temperature gradient.  As the temperature gradient decreases, the strength of the jet stream decreases and the growth of the low pressure system inhibited. 

Both the polar and sub-tropical jet streams are also affected by temperature shifts in the Pacific Ocean known as El Niño and La Niña. During the wintertime of an El Niño phase, the jet stream along the Pacific Coast of North America moves farther south and brings more storms and colder weather to California and the southwestern American states, while the American interior becomes dryer and milder.  In Canada, east of the Rocky Mountains, El Niño produces above average winter temperatures.  

During La Niña cycles, the United States can experience dryer winter conditions, both along the west coast and in the southeastern states.  In Canada, the jet stream retreats further north towards British Columbia in the winter, resulting in more precipitation in that province as well as in Ontario and Quebec, while the Prairie provinces may experience cooler than normal temperatures.

Next time you see the jet stream ribbon flowing across a weather map, remember to look for the colder and warmer regions of the atmosphere above and below that boundary. 

For more information about La Niña and El Niño cycles, the reader is referred to the article on this topic in the 2017 Celestial Planting Calendar. 

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Celestial Meteorology

by Dennis Klocek, 2018 Celestial Planting Calendar

To the casual observer the sun’s role in weather formation seems obvious, while the direct influence of the moon and stars seems remote or unlikely.  It is the purpose of this article to suggest that through a process of daily weather observation with an eye to the celestial aspects it is possible to see patterns emerge which point to significant relationships between celestial occurrences and meteorological activity.

Good starting points for observation are certain times during the year when extreme states of weather are consistently observable.  Take for instance the dog days in Leo.  Each year when the sun moves before the constellation of Leo on August 10 [currently August 11], the weather takes a distinct turn towards heat.  If we record the days of the most intense heat we will find that these days occur when both the moon and sun stand before fire constellations. This elemental phenomenon can be observed year after year.  In certain years however aspects of other planets interfere and this correspondence is not evident.  Nonetheless, it is a general rule that when both the sun and moon stand before fire constellations those days will be the hottest in the month.

...The movements of the sun in front of the zodiac create a monthly rotational rhythm of earth, air, water and fire.  A Pisces sun brings on the water element for rains and thaws at the time of the spring equinox.  As the sun moves before fiery Aries, skies brighten, air warms up and dries out, and storms tend to be short lived.  Those early heat waves in the spring can be expected in Aries, especially with a moon in a fire sign.  A Taurus sun ushers back in cooling trends and late frosts can be expected with strong planets in earth constellations.  At the summer solstice the sun moves before Gemini whose air/light energies clear the skies and give rise to stable, high pressure cells.  In certain latitudes the halcyon days of calm surrounding the solstice and the light breezes of midsummer are the very image of air/light.

The advance of the seasons thus keeps its pace with the rhythms of the stars.  The sun in Cancer brings a brief moist interlude after the brilliant skies of the sun in Gemini.  This bit of relief gives way to burning Leo and the dog days.  Leo’s heat in turn yields to the cool clear month of Virgo.  The turning of the temperature and the disturbance of the equinox will often make Virgo a month of strong weather changes.  In the central valley of California, Virgo is often the time of the first rain that breaks the dry season, which usually begins in Aires. 

Towards the end of Virgo, skies tend to be cloudy and temperatures are on the cool side.  Libra then brings clear skies and mild days and a touch of Indian summer.  This trend prevails for two weeks while the sun is before air and then the water element is ushered in by the sun moving before Scorpio.  Scorpio’s intense water energy promotes the growth of storms for the fall rainy season.
The winter solstice finds the sun standing before the fire constellation of Sagittarius.  At the winter solstice we can often observe the same calm period that we see at the summer solstice.  To be sure, some storm activity is often found in Sagittarius because of the increased activity of the polar low pressure area.  However, the most severe cold in the winter only occurs after the sun moves through Sagittarius into the cold earth constellation of Capricorn.  Even in California, Capricorn is the season of frost.  Record cold waves often occur when the sun and moon both stand before earth constellations.  The cold temperatures are then continued on into the constellation of Aquarius with its cloudless skies and windy days.  And so on into Pisces and the beginning of the spring thaw and rainy season.
The solar rhythm is the basis for seasonal weather patterns.  If we are to understand the birth and growth of storms and frontal passages we must look to other phenomena.  Pulsing through the grand solar rhythms we can find diverse areas of turbulent elemental force patterns that occur at predictable times.  The halcyon days of calm that surround the solstices in certain latitudes are an example of such regular phenomena.

Surrounding the equinoxes, however, are regular disturbances known to mariners as line storms.  A line storm occurs as the sun crosses the line of the equator at the fall equinox.  The storm then blows in a northwesterly direction away from the equator.  Hurricanes are examples of typical line storms.
In the northern hemisphere during the time of the fall equinox, it is also possible to connect the sun’s line crossing with the birth of storms that are not of a tropical nature.  By using the date of the equinox as a natal point for the birth of a disturbance, it is then possible to track the storm celestially on an ephemeris.  By assessing the nature of the celestial and planetary encounters that the storm will travel through, a flow chart of its character, strength, extent and duration can be obtained.  Each celestial encounter adds a particular elemental force to the storm. 

For instance, suppose that an equinox storm is forming off the southern coast of Alaska.  It begins to travel towards the southeast, and a day later the moon crosses the node.  The moon’s nodes are the places where it crosses the sun’s ecliptic and are therefore the places where the very disturbing energy of eclipses is released.  This disturbance encourages low pressure cells to develop more rapidly, especially if the node is near the full moon.  If the node is crossed during a period in which there is a cluster of six or seven planetary occurrences such as conjunctions and trines, then we can be sure that some disturbance is forthcoming in the next few days.  Each planetary aspect in a cluster must be carefully weighed for its storm potential.  However, it is safe to say that an equinox storm running into a cluster of trines and conjunctions is sure to be modified in a significant way.

For example, if we observe the activity of the planet Mars (“the precipitator”) we can see that it works to intensify conditions of precipitation.  When Mars is involved in a cluster of conjunctions or trines in front of water, then a definite acceleration of storm conditions is the result.  Cloudbursts and flooding can be expected.  However, the Martian character is masked when the starry background is earth or air.  Martian energy is easy to follow on an ephemeris and so it is a good planet to observe for storms.
Another planet that offers good data for observations, but for opposite reasons, is Venus.  Venus, a classic air planet, works to clear the skies and dispel overcast conditions.  When working out of a background of air, Venus gives rise to clear skies, bright puffy clouds and all manner of prismatic effects.  Sun dogs, halos, rainbows and luminescent clouds point to the influence of Venus.  But if Venus trines are conjunct in front of air with other air planets like Jupiter or Uranus, then her benign qualities can erupt into savage wind storms under the influence of these more violent planets.

... Due to its rapid orbit around the Sun, Mercury moves in front of a different constellation approximately every two weeks.  This two-week rhythm is a wonderful counterpoint to the more stately cadences of the outer planets.  Mercury enhances the heat element, especially when it is in retrograde motion.  At such times it is impressive to see the weather turn suddenly warm for two weeks and then shift to cold as Mercury moves before another constellation.  Its true character is revealed when conjunct or trined to Jupiter or Uranus in front of air or fire.  These aspects bring out the quick, flowing nature of Mercury.  Strong winds and rapid, churning clouds race across the sky.

Another planet that brings clouds racing across the sky is the tempestuous air planet Uranus.  Cloud building is its specialty.  Uranus energy is characterized by strong, expansive vertical movement of air.  These swift updrafts form large domes, castles out of which ride troop after troop of cloud cavalry units.  These dynamic clouds and the swift violence of the lightening bolts that they generate are sure signatures of Uranus.

The greatest mover of large air masses, however, is Jupiter.  If Jupiter is conjunct or trined in front of air and these aspects are supported by other air or fire planets, then savage windstorms result that can last for days.  The hot and dry Chinook winds find much support in difficult aspects of powerful planets like Jupiter (air) and Saturn (warmth).

The roles of the more remote planets (Jupiter, Saturn, Uranus, Neptune, Pluto) are much more subtle to perceive in weather phenomena than the roles of the more local planets (Mercury, Venus, Mars, the moon, and the sun.)  When two or three remote planets with similar elemental characters interact in a cluster their influence may more easily be determined.  Due to the slow orbits of these planets they tend to linger at points of turbulence (nodes and trines).  They also have longer stays in constellations, such as Saturn’s protracted stay at the node starting in the fall of 1974 and going until the spring of 1977.  Having a heat planet so strongly at the node turned the weather upside down and created severely cold winters that turned into drought-parched summers for a few years in a row...
Reprinted with the authors permission from Biodynamics, Winter 1986.

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Weather Wisdom from the Elders

Weather Wisdom from the Elders: Life with the Cosmos Explained

by Rosemary Tayler, 2017 Celestial Planting Calendar

Dew on the grass, no rain will come to pass. Dew forms on the surface of the grass as it cools. This occurs under clear skies at night when the heat radiates from the ground. If the sky remains clear, there will often be no rain, but if a weather system moves in during the day, then a change in the weather will follow.

A cow with its tail to the West makes the weather best, a cow with its tail to the East makes the weather least. Cows prefer not to have the wind blowing in their faces, thus they stand with their backs to the wind. Westerly winds usually mean that fair weather will be arriving or continue, and easterly winds usually mean unsettled weather will be arriving or continue. A weathervane or cowvane is thus a good a way of knowing what the weather will be for the next few hours.

Clear Moon, frost soon. When the night sky is clear, Earth’s surface cools rapidly – there is no cloud cover to keep the heat in.  If the night is clear enough to see the Moon and the temperature drops enough, frost will form. Expect a chilly morning!

If there is a halo round the Sun or Moon, then we can all expect rain quite soon. This halo is caused by refraction of the light through ice crystals that form from high cirrus clouds.  Cirrus clouds are usually the first clouds to appear before a weather front moves in.

Tomatoes seem to know what next winter will grow. If your tomatoes seem to have a lower meat content and many small seeds, they are likely expecting a dryer season whereby they leave extra seeds to improve the odds that some will hold over for the next year and sprout.

When clouds appear like towers, the earth is refreshed by frequent showers. Large, white clouds that look like cauliflowers or castles in the sky, indicate lots of dynamic weather going on inside. If the clouds start to swell and take on a grey tint, they will likely turn into a thunderstorm.

No weather is ill, if the wind be still. Calm conditions, especially with clear skies, indicate the dominance of a high pressure system moving in. Because high pressure systems are broad regions of descending air, they discourage the formation of clouds, wind and precipitation. Calm conditions, however, may also result from a circumstance referred to as “the calm before the storm,” in which a large thunderstorm cell to the west may be updrafting the westerly surface wind before it arrives. This situation is easily identified by looking to the west — such an approaching storm will be certain to occur. 

When windows won’t open, and the salt clogs the shaker, the weather will favor the umbrella maker. Moisture in the air causes wood to swell, making doors and windows sticky. Salt is a very effective absorber of moisture. With a high level of moisture in the air, the likelihood of precipitation is increased.
Bees nesting in trees, means lots of snow. When hornets, wasps and bees build their nests higher than normal in trees, expect lots of snow.

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La Niña: How It Might Affect 2017 Weather

Interview with David Phillips, Senior Climatologist for Environment and Climate Change Canada

by Rosemary Tayler, 2017 Celestial Planting Calendar

La Niña, which is Spanish for “the girl child,” is characterized by the cooling of the equatorial waters in the central Pacific Ocean, near the International Dateline. As this water mass cools down to at least 0.5° Celsius (0.9° Farhenheit) below normal, it gradually influences the atmosphere overhead and the resulting movement of weather systems around the world. 

Its counterpart, El Niño, which is Spanish for “the boy child,” has generally the opposite effect. A warm pool of water over the Western Pacific Ocean moves eastward to the South American coast. The exceptionally mild winter across Canada in 2015-2016 was consistent with a strong El Niño effect. 

This rhythmic cycle of cooler followed sometimes by warmer oceanic waters in the Pacific is not necessarily consistent year to year. In some years, there is a neutral pattern, sometimes referred to as La Nada, when sea surface temperatures stay within a ½° C (1°F) of normal. 

Recently scientists have determined the Super El Niño which has been in effect since March 2015 peaked in December 2015–January 2016 and all but disappeared at the end of the spring in 2016. It now appears that there is a move towards cooler waters in the central Pacific Ocean. It is at present (June 2016) too early to determine whether this cooling off phase will be weak, moderate, intense or reverse to warmer waters. 

The La Niña phase is generally not as strong as the El Niño phase but it often lasts longer, even as long as two or more years. Regions that saw floods or droughts with El Niño might likely see the reverse with La Niña.

In the few months before the start of 2017, the atmospheric patterns will likely catch up to the cooler oceanic waters and the weather will become cooler than normal. There is always this dance between the ocean and the atmosphere; in this case, it takes a few months for the air currents overhead to adjust to the ocean water temperatures. 

How do these rhythms impact on gardeners and farmers? What will the weather be like in the winter and spring of 2016-2017? 

Generally La Niña encourages more tropical storms in the North Atlantic. On average there are 11 tropical storms and the La Niña effect might increase this to 15 tropical storms. Not all of these will necessarily impact land; they may stay out in the water as “fish storms.”

In Western and Central Canada, including Ontario and Quebec, people will likely experience a colder than normal 2016-2017 winter with it lasting longer into spring than the previous year. 
There are many factors involved in such an outlook, over and above the La Niña effect.  However, it is fair to say that compared to the winter of 2015-2016, when the El Niño effect almost cancelled winter, the upcoming winter of 2016-2017 will be colder and longer, possibly resulting in a later spring due to an accumulation of more snow in most parts of Canada. Farmers may be delayed getting onto their fields in the spring as the soil may remain colder. In addition, water content of soils and the supply of water in creeks, rivers and reservoirs might be higher, and the likelihood of spring flooding might be greater.

As La Niña wanes, the final fall in this cycle generally has some warmth to it, which might compensate for the previous delayed spring planting.

As of August 2016, the mass of cooler air in the central Pacific Ocean is still building and it appears this cooling phase may be weak. 

For more information, check out the La Niña Wikipedia website, as well as El Niño Shifting to La Niña in 2016 by Gil Gullickson. 

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