References are indicated thus: ⁽¹⁾ refers to note 1 at the bottom of this page.
The following is a summary description of the earth:
The earth is a rocky planet comprising a number of separate layers (Fig 1) with a volume of 1.08321E+21m³, a mass of 5.966585E+24kg, and an average density of 5508.2583kg/m³. It was created from the rocky rubble left over from the ignition of our sun about 4.6 billion years ago.
The heaviest naturally⁽¹⁾ occurring element in the universe is iron. During the early stages of the earth's creation the majority of its rocky bulk was molten, allowing its heaviest element(s) to gravitate to its centre where they formed its core.
At about 6500K the earth's core is hotter than the surface of the sun and well above the melting point of iron⁽²⁾ (including its alloys) on the earth's surface. The massive pressures at the earth's core, however, ensure that the iron-rich (≈90%) inner core exists as a solid even at 6500K. The core's molten outer layer, which is also mostly iron, is the source of the iron in the earth's mantle, plates and crust. Whilst the outer core provides the driving force (drag) that causes the inner core to rotate it also acts as a lubricator allowing its rotational speed to vary with respect to the mantle and the plates.
About four billion years ago the earth's surface cooled sufficiently to form a crust but the heat and pressure generated by convection in the mantle material below the plates (plumes) needed release. Random weak points in this crust released mantle pressure bringing with it molten rock that cooled at the surface adding material to the plates and crust. This surface deposition began to move the crust locally (Fig 1) but as time progressed, these random weak points joined up to create the mid-ocean ridges (Fig 2) we have today.
The earth's sub-crust divided into plates as the mid-ocean ridges joined up. Where two adjacent plates were pushed together, the crust squeezed between them created the continental land masses (Fig 2). Subduction zones formed at the edges of these land masses where plate material is pushed down into the mantle. The speed of movement of these plates varies around the earth but is today generally between 2cm and 15cm per year dependent upon plate size and subduction resistance. It is probable that these plates moved faster in the past when the earth had more internal heat energy.
Volcanoes release the pressure generated above subduction zones, and the mid-ocean ridges relieve pressure in the mantle. Mantle plume pressure is relieved in the middle of large oceanic plates (e.g. Pacific) by volcanoes over Hot-Spots but whilst plates move the plumes remain in the same place, generating island chains (e.g. Hawaii).
Two of the most abundant substances in the earth: carbon and oxygen, (both of which are lighter than iron) were fixed in the rocks in various forms at its creation. The earth's mantle converts these two elements into CO₂.
For most of its life, the earth's atmosphere was predominantly CO₂ (see Life on Earth below).
Despite the dominance of a greenhouse gas in the earth's atmosphere with virtually no free oxygen for the first half of its existence:
a) the earth's surface water has always been predominantly liquid
b) life on earth began during this period
As far as we know, other than during periods of glaciation ('ice-ages') there was no ice at the North Pole until around ten million years ago.
A Definition: A rocky planet with a rotating iron rich core, a hot molten mantle and a silica crust divided into moving plates. Mantle and plate pressures are relieved via subduction zones, mid-ocean ridges, volcanoes and earthquakes. It has surface water in liquid form and its natural atmosphere is predominantly CO₂ (it contains no life)
Life is a passenger on earth that probably began as underwater bacteria at hot volcanic fumaroles less than four billion years ago and evolved into single-cellular life forms about 500 million years later. Over three billion years ago stromatolites appeared and were probably the first (and maybe only) photosynthetic plant life on earth at that time in what was a CO₂ rich atmosphere with virtually no free oxygen. Stromatolites eventually covered most of the earth's shallow water regions.
Until about 2.5 billion years ago, all the O₂ produced by Stromatolites was absorbed by iron dissolved in the seawater⁽³⁾ preventing free O₂ from collecting in the atmosphere. As soluble iron in the water diminished, free oxygen began to release directly into the atmosphere. At that time there were no creatures, plants or soil on the earth's dry land.
Between 2.5 billion years ago and 600 million years ago, the oxygen produced by Stromatolites mixed with the CO₂ already present in the atmosphere to a point where O₂ eventually became much more abundant and oxygen breathing, single cell organisms began to populate the earth's oceans. Whilst these single-cell organisms were probably the only creatures living on the earth during this period, complex multi-cellular underwater plant life developed and proliferated in shallow water regions.
More than 600 million years ago the super-continent 'Gondwana' formed, a large part of which was over the South Pole, generating a massive global ice-age and Killing 70% of all extant life.
When this ice-age ended ≈580 million years ago multi-cellular animal life appeared in the water for the first time⁽⁴⁾. About 50 million years later predator and prey lived side by side in the sea.
About 450 million years ago plants left the water and moved onto dry land for the first time. Animals followed the plants out of the water more than 50 million years later⁽⁵⁾.
300 million years ago land plants proliferated to the extent that a large proportion of the available CO₂ was extracted from the atmosphere plunging the earth into a 60 million year-long ice-age during which a massive eruption occurred in Siberia (≈250 million years ago). Together these two events killed 90% of all life on earth.
The dinosaurs appeared on earth for the first time 235 million years ago, and remained the dominant animal life form for 170 million years. During this time mammals existed as nocturnal shrews.
About 65 million years ago, a 12km meteorite impacted with the earth in Mexico and the dinosaurs became extinct, which may or may not have been a coincidence. Whilst the meteorite impact would have been extremely damaging to the earth's atmosphere, many believe it should not have been sufficient to kill off all the dinosaurs. However about the same time, the Deccan Traps began to form during a period of violent volcanic activity lasting about one million years. It is currently believed that a mantle plume was responsible for this eruption. However, it is also possible that the meteorite impact in Mexico, on the other side of the planet, rung the earth's crust (like a bell) and the vibrations all converged at the Deccan Traps weakening the plates and the crust sufficiently to release mantle pressure that should otherwise have been contained or released gradually.
Mammals evolved much faster after the extinction of the dinosaurs, and have remained dominant ever since.
Early versions of the human race first appeared about four to five million years ago, all of which gradually died out. Neanderthals were the most recent pre-Homo-sapiens to have existed and they died out around 30 to 35 thousand years ago.
The first Homo-sapiens appeared about 200,000 years ago and have therefore been passengers on the earth for 0.0044% of its existence.
All the numerical statements made in this section are based upon an analysis of the Earth's Atmosphere, in which you will see that the most important gases in the earth’s atmosphere are:
Nitrogen: Its most important function concerning life on earth is to maintain the planet’s surface temperature. If the atmosphere’s nitrogen diminished significantly the earth would cool down, perhaps dangerously so
CO₂: Is by far the most important life-giving gas in the atmosphere, without it there would be no plants and therefore no oxygen and therefore no animal life. Life on earth could survive a significant increase in levels of CO₂⁽¹²⁾ before it would become adversely affected
Oxygen: Is the next most important atmospheric gas, as animal life on earth needs it to survive
Between 4.5 billion and 2.5 billion years ago, the earth's atmosphere was predominantly hydrogen, carbon dioxide, water vapour, methane, carbon monoxide, sulphur dioxide, sulphuric acid, nitrogen oxide, amonia, and other toxic gases. Except during events of unusually high volcanic activity, the trend for the earth's natural CO₂ production rate has continued to decline as its internal heat energy is released.
CO₂ is extremely important for life on earth and was, in fact, singularly responsible for its creation. Any decline in its mass in the earth’s atmosphere will result in a consequent decline in life on earth.
Between ≈3.5 billion and ≈2.5 billion years ago, stromatolites converted atmospheric CO₂ into oxygen, virtually none of which reached the atmosphere during this period⁽³⁾. As such, atmospheric CO₂ declined and the earth cooled due to a reduction in volcanic activity as core heat energy was lost.
As atmospheric temperature declined, water vapour decreased reducing the sulphuric acid. During this period, virtually all oxygen generated by the stromatolites was trapped by oxidising iron dissolved in the oceans.
By 2.5 billion years ago, all the surface iron on the earth had been oxidised and free oxygen (O₂) was being released directly into the atmosphere. At his time the earth's atmosphere contained ≈25 times more O₂ than CO₂
According to Bob Berner⁽⁶⁾, about 500 million years ago CO₂ in the earth's atmosphere was ≈25 times greater (≈0.93%) than it is today (≈0.037%). If one assumes that prior to the glaciation of 600 million years ago CO₂ declined at a similar rate as it has since, CO₂ production (by the earth) is probably falling at the rate of ≈2.2E-09% each year. Despite this decline in CO₂ as the earth gets older, spikes⁽⁶⁾ continually occur with variations in plume and volcanic activities.
This decline in the earth's CO₂ generation will continue until it loses all of its internal heat energy. At which time the core will have stopped revolving and the earth will become a solid rock with no atmosphere and barren of all life just as Mars did four billion years ago.
The earth's atmosphereic climate is controlled by the relative location of its land masses and the interspatial areas of ocean and associated currents⁽⁹⁾. Life extinctions have generally occurred when all the land masses have converged at the same place (e.g. Pangea and Gondwana and others). It is likely therefore, that life as we know it on earth has until the next extreme glaciation, which will probably occur when the next supercontinent is formed, at which time our survival will be at serious risk.
The main strata of earth's principle atmospheric gases are shown in Fig 3
Because the earth's gravity decreases with altitude (see also CalQlata's UniQon calculator) all atmospheric gases are most dense (highest pressure) at the earth's surface reaching a density (and pressure) of zero at their individual ceilings.
Together: density, quantity, gravity, and centrifugal force ('F' Fig 4) define the pressure and ceiling variations for each gas in the earth's atmosphere. The lower layers (excluding the thermosphere); i.e the troposphere, stratosphere and mesosphere, are thicker at the equator where centrifugal force and higher atmospheric temperature have the greatest effect but this growth at the equator causes the atmospheric layers to thin out at the poles as the gas molecules move around to balance pressure with centrifugal force with gravity. This thickening at the equator and thinning at the poles has always been a natural phenomenon of the earth's atmosphere (see Earth's Atmosphere).
The ionosphere (80km to 500km) and the exosphere (500km to 1000km) are not included in this assesment as they do not contain molecules that are essential to life on earth.
The earth’s atmosphere is simply a mixture of gases. The term 'Weather' is used to describe the localised behaviour of these gases in terms of temperature, pressure and movement.
Refer to Earth's Atmosphere for the theory:
Firstly; assume that the earth’s surface is spherical and smooth and all of its materials are identical and all at the same elevation, plate tectonics does not exist and the earth is always a fixed distance from the sun ...
Each atmospheric gas will occupy all the space available to it and behave independently of all other gases in this space at its own partial pressure. Given sufficient time ...
... all the earth’s atmospheric gases will expand to fill its container (i.e. gravity)
... the atmospheric gases over water will exist at a different pressure to that over land
... if the total mass of the earth’s atmospheric gases are as we find today, the pressure of the gases at the surface will be ≈1bar
... if the surface temperature is above 0°C and below 100°C most of the water will remain in liquid form on the surface
... evaporation will cause some of the surface water to exist in the atmosphere in vapour form⁽¹³⁾
Now rotate the earth on its axis. Friction between the gases and the earth’s surface will cause the temperature to rise slightly (at the surface) and generate movement in the gases.
Now create undulations in the earth’s surface (mountains and valleys). The earth’s atmospheric gases, which are more dense at the surface will move very differently as they pass over the undulations altering pressures locally. The gases will build up pressure before hitting a mountain, drop as they pass over the other side and equalise later as they mix with the rest of the atmosphere. Given that the gases can hold more water molecules in gaseous form at high temperature (temperature increases with pressure) than at low temperature, as they pass over a mountain the pressure drop will lower the amount of water the atmosphere can hold (lowering its saturation temperature). As this happens, the water will first form a vapour (tiny droplets) in the atmosphere appearing as clouds. Some of the sun’s radiated heat will be trapped by the water vapour before it can pass through the cloud lowering the temperature (and hence the pressure) of the atmospheric gases below the cloud. As the pressure drops still further and the gases move away from the mountain, the temperature may eventually fall to a point whereby the water will collect as a liquid (below its dew-point) and fall towards the earth’s surface under the influence of gravity; the higher the mountain the greater this effect.
Now add plate tectonics to the earth’s activities. In places where the earth emits gases, heat and water into the atmosphere, temperatures and pressures and water retention properties will differ changing the properties of the atmosphere locally.
Local variations to pressure and temperature of the earth’s atmospheric gases from region to region alter their ability to retain water molecules. The changes to pressure also generate movement of these gases, which appears as wind.
Finally, rotation of the earth means that any point on its surface warms during the day and cools during the night, which is the reason clouds build up at dusk in warm regions as the atmosphere cools and vanish after dawn when the atmosphere warms varying saturation/dew-point. Along with the variation in the earth’s distance from the sun during the year and the tilt of its axis (currently about 23°) and the spherical shape of the earth’s surface, temperatures and pressures will constantly change at all latitudes from hour to hour, day to day and year to year warming up and cooling down the earth’s gases and surface materials locally. Gases take time to equalise their temperatures and pressures so the continually changing conditions of the earth’s surface mean that this equalisation cannot occur, which is lucky for life on earth, as without this weather most of the life on its surface would not exist.
Atmospheric temperature is generated by the sun’s radiated heat and from internal friction within the earth. This heat is trapped by each atmospheric gas according to its ability to retain heat (specific heat capacity). The most abundant gas (nitrogen) accounts for almost 80% of the earth’s atmospheric heat and the least abundant gases (carbon and hydro-carbon, sulphides, ammonia, ozone, etc.) have negligible effect on the earth’s surface heat retention. However, CalQlata would like to point out that at least one of these minor gases is vital for both the earth’s weather and life on its surface; CO₂. It would be harmless to life on earth at ten times its current levels without any significant effect on surface temperatures.
As a result of the laws of motion for elliptical orbits, including that governing equal time vs equal swept area, earth's orbit looks like the path shown in Fig 5, where:
greatest radius = 1.52054683E+11m
least radius = 1.47100176E+11m
orbital path = 9.39758258E+11m
orbital period = 31558149.77s
eccentricity = 0.016561679
parameter = 2 x 1.49536402E+11m
focal distance = 1.47100176E+11m
Milankovitch has already pointed out that it is not the accumulation of ice and snow during winter that determines the climate of a planet (or any part of it), but the ability for it to melt (totally) during summer. Therefore, despite southern summers currently receiving less heat energy per square meter, they last over 23% longer than those in the north, which is the reason why the weather is better at latitudes south of the equator than those in the northern hemisphere.
Southern Antarctica is only colder than the northern Arctic because Antarctica is a land mass which retains permafrost whilst the ocean currents warm the water below the arctic ice-flow
What is generally referred to as the earth's protective ozone layer is actually the stratosphere (Fig 6) which is mostly composed of nitrogen and various forms of oxygen (N₂ doesn't react with UV radiation).
When an oxygen molecule (O₂) anywhere in the earth's atmosphere is bombarded with UV radiation from the sun it splits into two oxygen atoms (2O). The two oxygen atoms then attach themselves to other oxygen molecules forming the highly unstable ozone molecule. Due to their instability, as the heavy (2.14kg/m³) ozone molecules fall through the stratosphere and into the troposphere most of them degrade to oxygen molecules and oxygen atoms (O₃ → O₂ + O and O + O → O₂) before they reach the earth's surface.
Most UV radiation is not absorbed in the upper region of the oxygen layer (the stratosphere) as this region holds only 17% of earth's atmospheric oxygen. However, most of the UV radiation will have been lost Ozone production before it reaches the earth's surface (within the troposphere). Obviously more UV radiation will get through to the earth's surface at the poles than the equator because this is where the oxygen layer is much thinner (see The Atmosphere Today above).
Towit; it is not ozone that protects the earth from UV radiation it is the oxygen molecules in the earth's atmosphere. Ozone is simply an unstable by-product of the protection process, most of which occurs in the troposphere.
Furthermore, that which has to date been referred to as a 'hole in the ozone layer' over the poles is actually the misinterpretation of a natural phenomenon that has nothing to do with mankind's activities (see Earth's Atmosphere).
CO₂ in the earth's atmosphere is trapped in rain, washed into rivers on the surface of the earth and out into oceans. CO₂ is also emitted into the oceans from the mid ocean ridges and other submarine volcanoes. The ocean water (with all of its entrained gases) that is dragged down with the earth's crust into subduction zones lowers the melting point of the rock and is ejected out through volcanoes above subduction zones, along with molten rock and all the entrained gas into the atmosphere. This is called the long-term carbon cycle.
Whilst CO₂ is absorbed by marine plants and organisms it is also continuously replenished. As the mid ocean ridges have been emitting gases into the oceans for at least four billion years it should be safe to conclude that they are now all but saturated with such gases; therefore, today most of the CO₂ and other gases emitted by the mid ocean ridges probably pass right through the oceans and end up in the atmosphere.
The ocean's prime function...
for the earth is to lubricate subduction zones.
for plant life is to provide water and CO₂.
for animal life is to provide water.
The earth's ocean activity is due to differential temperatures & densities, tidal movement (from the moon's pull) and/or the anti/clockwise natural movement of weather and water in the northern and southern hemispheres. For example:
The Gulf Stream (northern hemisphere):
Surface water in the Mexican Gulf (near the equator) is about 20°C warmer than it is around the arctic polar ice-cap making the water less dense in the Mexican Gulf than at the North Pole due to its higher temperature, but causing the salt content to be slightly higher due to evaporation. Seawater exits the gulf and flows towards the North Pole due to natural rotational direction in the northern hemisphere (clockwise). As the temperature of the surface water decreases near the polar region, along with its high salt content, its density is sufficient to cause it to sink. Whilst sinking, it drags more water out from the gulf generating the current.
The Gulf Stream will continue to operate whilst there is a significant difference between the surface water in the Mexican Gulf and that at the North Pole, even if the temperature of the surface water at the equator is around 70°C and there is no polar ice cap. In fact this current will continue to operate unless something occurs to significantly reduce the difference between the Gulf Stream water density and that at the North pole. For example:
In the event the polar ice cap grows significantly during a period of glaciation (ice age), as glaciers break off from the polar cap, float south and melt, the density of the gulf stream water will drop (glaciers are made from fresh water) arresting the sinking process and switching off the current.
All the earth's ocean currents operate similarly albeit the circular motion in the southern hemisphere will be anti-clockwise. When these currents switch off during long periods of glaciation, weather patterns will also come to a halt killing off much of the life on land and in its oceans until the temperature rises again switching the currents and weather patterns back on.
It is therefore far better for the continuation of life on earth (as it is today) for the earth's surface temperatures to remain high or even increase (see Pollution; Note 2) than to allow it to continue to fall.
Planets without moons (e.g. Mercury, Venus, etc.) normally rotate at a similar rate to their orbit around the sun as a result of the sun's gravitational pull. If you imagine gravity replacing the cord attached to a ball that you swing around your head, the same face of the ball will always point inwards. A planet is slightly more complicated than a ball, however, having properties that vary throughout their mass and in active planets (i.e. those with a molten outer core) these properties will alter slightly as gravitational influences (from other planets) fluctuate during its orbit, thereby varying its axis rotation rate.
A moon orbiting a planet will cause the planet's rotation to increase according its moon's gravitational influence. For instance:
Phobos is very close to Mars so it will travel around the planet very fast. Mars is now solid (no molten internal layer) so Phobos must rotate the entire mass of the planet. Phobos has a much smaller mass than Mars so its gravitational influence is quite small. Therefore Phobos will travel around Mars much faster than the Mars rotates on its axis.
The earth has solid plates (including the crust) approximately 80km thick, a semi-molten mantel, a molten outer core and a solid inner core. The earth's moon is essentially trying to rotate the mass of the earth's plates and overcome drag (between the plates and the semi-molten mantle) rather than the entire planet and as the mass of the moon and the mass of the earth's plates are similar, the moon will rotate round the earth at approximately the same rate as the rotation of the earth (approximately).
Rotation of the earth's plates will drag its core around with it due to the viscosity of the molten outer core material causing the inner core to rotate but at a different rate than its plates; i.e. slower. This differential rotation between the core and the plates, both of which are rich in iron, is what generates the planet's magnetic field, likening the process to an electric motor or generator and assuming that the Curie temperature of iron (1316K)⁽²⁾ rises with pressure.
Its magnetic field protect the earth's surface from solar radiation, the interaction of which manifests itself as the Aurora Borealis (southern and northern lights). The north and south poles have, as far as we know, always flipped at irregular intervals⁽¹⁰⁾ and will continue to do so until the earth's internal heat energy is insufficient to keep the inner core molten and activate mantle plumes, which together allow the inner core to rotate freely. After which, the earth will become a barren solid rock and the (non-existent) life on it will no longer need this protection.
The earth is currently tilted at 23.4° from its vertical axis (relative to the plane of its orbit around the sun). This tilt is generated by a combination of the earth's natural gyroscopic tilt and the righting effect of its moon's gravity. Together, these two opposing forces maintain and protect the angle of tilt from the gravitational influence of the sun and the other planets (in the solar system). This tilt will become more erratic as the moon moves gradually further away from the earth⁽¹¹⁾ increasing the relative effect of other inter-planetary gravitational influences.
CalQlata has not yet found any convincing research to show how long it takes for the poles to flip or the loss of field intensity during the changeover process or even what causes it. It is possible that when a flip does take place, life on earth may be unprotected (from solar radiation) until it has been fully re-established.
It is also possible that pole flipping occurs when the core's rotational speed alters with respect to the rotation of the earth's plates (i.e. the core rotates faster than the plates) and that this change in speed may be caused by a change in external gravitational forces, e.g. that of the sun, the moon and the other planets, in which case it should be predictable (refer to 'Milankovitch'; Ice-Ages below).
It is also possible that the earth itself could flip on its axis due to extreme extra-terrestrial gravitational influences on the earth's tilt and that this may be the causative event, just as appears to have happened to the planet Venus in the past.
'Ice age' (or glaciation) is an expression used to describe a condition that exists when the earth's land surface temperature remains largely below zero all year round and for many years. These periods can be short (a few thousand years) to long (a few million years) and mild (permanently <0°C) to extreme (permanently <-50°C).
Ice ages have occurred as a result of:
a) all (or most of) the continental land masses converging at or around one of the poles completely destroying otherwise variable weather patterns
b) extraordinary planetary (and solar) influences changing the earth's tilt and its seasons
c) plant life extracting all the CO₂ from the atmosphere (e.g. 300 million years ago), but this is a highly dubious claim due to the fact that CO₂ holds such a tiny percentage of the earth's atmospheric heat energy
It is probably relatively straightforward to predict the next occurrence of a) above from known tectonic plate orientation and movement, and b) has been successfully calculated by Milankovitch and verified by evaluation of the Barbados terraces.
Massive Ice-ages (e.g. 300 million and 600 million years ago) appear to have been responsible for the extinction of all extant multi-cellular animal life on those occasions.
You will find further reading on this subject in reference publications(28, 28 & 30)