“CHANGES IN THE WORLD’S CLIMATE

A complete account of the causes of these great climatic fluctuations has still to be worked out, but we may perhaps point out some of the chief of them. Prominent among them is the fact that the earth does not spin in a perfect circle round the sun. Its path or orbit is like a hoop that is distorted; it is, roughly speaking, elliptical (ovo-elliptical), and the sun is nearer to one end of the ellipse than the other. It is a ta point which is a focus of the ellipse. And the shape of this orbit never remains the same. It is slowly distorted by the attractions of the other planets, for ages it may be nearly circular, for ages it is more or less elliptical. As the ellipse becomes most nearly circular, then the focus becomes most nearly the centre.
When the orbit becomes most elliptical, then the position of the sun becomes most remote from the middle or, to use the astronomer’s phrase, most eccentric. When the orbit is most nearly circular, then it must be manifest that all the year round the earth must be getting much the same amount of heat from the sun; when the orbit is most distorted, then there will be a season in each year when the earth is nearest the sun (this phase is called Perihelion) and getting a great deal of heat comparatively, and a season when it will be at its farthest from the sun (Aphelion) and getting very little warmth. A planet at aphelion is travelling its slowest, and its fastest at perihelion; so that the hot part of its year will last for a much less time than the cold part of its year. (Sir Robert Ball calculated that the greatest difference possible between the seasons was thirty-three days.) During ages when the orbit is most nearly circular there will therefore be least extremes of climate, and when the orbit is at its greatest eccentricity, there will be an age of cold with great extremes of seasonal temperature. These changes in the orbit of the earth are due to the varying pull of all the planets, and Sir Robert Ball declared himself unable to calculate any regular cycle of orbital change, but Professor G. H. Darwin maintained that it is possible to make out a kind of cycle between greatest and least eccentricity of about 200,000 years.

But this change in the shape of the orbit is only one cause of the change of the world’s climate. There are many others that have to be considered with it. As most people know, the change in the seasons is due to the fact that the equator of the earth is inclined at an angle to the plane of its orbit. If the earth stood up straight in its orbit, so that its equator was in the plane of its orbit, there would be no change in the seasons at all. The sun would always be overhead at the equator, and the day and night would each be exactly twelve hours long throughout the year everywhere. It is this inclination which causes the difference in the seasons and the unequal length of the day in summer and winter. There is, according to Laplace, a possible variation of nearly three degrees (from 22° 6’ to 24° 50’) in this inclination of the equator to the orbit, and when this is at a maximum, the difference between summer and winter is at its greatest. Great importance has been attached to this variation in the inclination of the equator to the orbit by Dr. Croll in his book Climate and Time. At present the angle is 23° 27’. Manifestly when the angle is at its least, the world’s climate, other things being equal, will be most equable.

And as a third important factor there is what is called the precession of the equinoxes. This is a slow wobble of the pole of the spinning earth that takes 25,000 odd years. Any one who watches a spinning top as it “sleeps,” will see its axis making a slow circular movement, exactly after the fashion of this circling movement of the earth’s axis. The north pole, therefore, does not always point to the same north point among the stars; its pointing traces out a circle in the heavens every 25,000 years.”

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Leif Svalgaard writes to share the predicted view of the total solar eclipse on Apr 8

https://www.predsci.com/corona/apr2024eclipse/home.php

This is our latest prediction of the solar corona for the April 8, 2024 total solar eclipse. The above images show two versions of the predicted white light brightness in the corona at totality; the left is with solar north up, and the right is for Dallas, Texas. Click on the link to see the orientation of the corona for your location. The images have been processed with a radially-graded filter, to approximate what a human eye might see during the eclipse.

The Sun is near the maximum phase of the solar cycle, so the solar magnetic field is evolving rapidly. To better capture the dynamic nature of the Sun at this time, we are using a time-dependent MHD model that is updated in near real-time with the latest measurements of the surface magnetic field.T hese animations show how the Sun and our prediction are evolving with time. The animation on the left shows how the prediction at totality has evolved to the present. The animation on the right shows the modeled evolution of the Sun from the start of the prediction.

These animations are the same as those above but show a special visualization of the three-dimensional (3D) magnetic field. By tracing magnetic field lines at extremely high resolution, we can calculate a 3D map of the so-called squashing factor (Q) – a scientific measure designed to indicate the presence of complex structuring in the magnetic field. We then integrate the map along the line-of-sight, with special weightings to create a composite that resembles solar eclipse images. This is intended to highlight the inherent complexity of the Sun’s magnetic field and its intimate connection to visible emission from the solar corona.

Check out: https://www.predsci.com/corona/apr2024eclipse/home.php