The Ocean and Climate

http://oceanworld.tamu.edu/resources/oceanography-book/contents.htm

§  Intertropical Convergence Zone- area encircling the Earth near the equator where winds from the Northern and Southern hemispheres come together

§  So much heat is released as rain in the intertropical convergence zone that it drives much of the atmospheric circulation (this circulation is called the Hadley circulation)

§  Winds drive ocean currents and together they carry heat from the tropics to the polar regions

§  97% of Earth’s water is in the oceans

§  The ocean and ocean life control the amount of carbon dioxide in the Earth’s atmosphere and they dominate the Earth’s carbon cycle

§  Most available carbon is in the ocean- the ocean has 50X more carbon than the Earth’s atmosphere

§  Approximately half of the Earth’s primary production occurs in the ocean

§  Almost half of the carbon dioxide emitted into the air by the burning of fossil fuels is absorbed by the ocean

§  Carbon dioxide is absorbed into cold ocean waters by the Arctic and Antarctic. As the cold water sinks, it carries the carbon dioxide away from the atmosphere. Many years later the water is gradually pulled closer to the surface by mixing in the ocean. When it gets to the surface in warm areas, the carbon dioxide is released back into the atmosphere. This process allows the ocean to store great quantities of carbon dioxide for many centuries

§  Phytoplankton release dimethyl sulfide (which is converted to sulfate aerosols) which changes the way clouds are formed in the atmosphere

§  1/3 of the sunlight that reaches Earth is reflected back into space by clouds

The Cosmos

Jones, B.W. Life in the Solar System and Beyond. 2004. Praxis Publishing.

Ø  The Milky Way Galaxy contains about two hundred thousand million stars

Ø  There are billions of galaxies in existence

Ø  Perihelion- point in the orbital ellipse of a planet at which it is closest to the sun

Ø  Aphelion- point in the orbital ellipse of a planet at which it is furthest from the sun

Ø  Planets move the fastest near the perihelion because the gravitational pull of the sun is greatest there (they move the slowest at the aphelion)

Ø  Orbital period- time it takes for a planet to go around its orbit once

Ø  Pluto’s orbital period is 248 years

Ø  The asteroid belt is between the orbits of Mars and Jupiter

Ø  Most asteroids are rocky and a few kilometers in radius

Ø  Comets are mixtures of rocky particles and icy materials

Ø  Comets originate in two regions:

1.       The Edgeworth-Kuiper belt (located near the orbit of Neptune)

2.      Oort Cloud (which is located nearly one light year from the sun)

Ø  The four innermost planets (the planets closest to the sun) Mercury, Venus, Earth and Mars are termed terrestrial planets because their composition is dominated by rocky materials

Ø  Volatile substances, such as water and gases, make up only a small fraction of the terrestrial planets’ masses

Ø  Jupiter and Saturn are termed the giant planets, and are dominated by hydrogen and helium (Uranus and Neptune are also termed giant planets, but water makes up over half the masses of each with hydrogen and helium only contributing about 10% of their masses- they are also sometimes called the water planets)

Ø  Pluto is an icy planet, made up of water ice, methane ice and other types of ice

Ø  Mercury has a surface that is scarred by impact craters

Ø  A surface becomes more cratered with the passage of time unless geological processes such as volcanism or weathering remove the craters, therefore the abundance of craters on Mercury is evidence of a lack of geological processes

Ø  Lack of weathering on Mercury is consistent with the near absence of an atmosphere- also suggests that Mercury has not had much of an atmosphere in the past

Ø  The sun-facing surface of Mercury can reach temperatures of 700 K (800 F) but because of a lack of atmosphere and its slow rotation, night-time temperatures can reach lows of 90 K

(-297 F)

Ø  Venus is shrouded in clouds consisting mostly of sulphuric acid droplets

Ø  The atmosphere of Venus is high, thick and dry and consists of carbon dioxide

Ø  Venus’s atmosphere creates a greenhouse effect that raises the average surface temperature to 733 K (860 F) ***Wow! It’s hotter than Mercury even though it’s further from the sun! Cool!***

Ø  There are few surface craters on Venus, but many volcanoes and widespread evidence of volcanic activity (this volcanism along with atmospheric weathering is responsible for the obliteration of impact craters)

Ø  70% of Earth’s surface is covered in oceans

Ø  Clouds of water droplets often cover approximately ½ of Earth’s surface

Ø  Main constituents of Earth’s atmosphere are oxygen, nitrogen and traces of carbon dioxide

Ø  Plate tectonics are unique to Earth

Ø  The atmosphere of Mars mainly consists of carbon dioxide

Ø  Mars has a thin atmosphere and has sparse cloud cover. This, in combination with its distance from the sun, make Mars a cold planet

Ø  Temperatures on Mars range from 283 K (50 F) at the equator to 173 K (-148 F) or lower at night

Ø  The northern hemisphere of Mars shows evidence of geological activity (could have been from only past activity) and few impact craters whereas the southern hemisphere displays little evidence of geological activity and has many impact craters and also bears features that suggest Mars was once a warmer, wetter place **Weird**

Ø  Water, in the form of ice, is present on Mars at the polar caps, and as frost at night. Also, Mars has some clouds formed of water ice

Ø  There is probably liquid water under the surface of Mars

Ø  Jupiter has no proper surface at all- as one moves deeper towards the core of Jupiter, the atmosphere (mostly hydrogen and helium) becomes denser and hotter forming a global ocean of hydrogen and helium

Ø  Heavy elements are probably concentrated near the center of Jupiter and the core is probably liquid water and liquid rock

Ø  Jupiter’s uppermost clouds are icy particles of ammonia colored in some unknown way and formed into bands and whorls by atmospheric circulation

Ø  Saturn is similar to Jupiter, but smaller, more enriched in heavy elements, and the cloud features are subdued by atmospheric haze

Ø  Uranus and Neptune also have atmospheres rich in hydrogen and helium, but these are not the dominant elements

Ø  The surfaces of Uranus and Neptune are probably made up of liquid water, ammonia, and methane, but the surfaces are hidden by atmospheric haze and clouds

Ø  Most of Pluto’s volume is probably water ice and rocky materials with a concentrated core

Ø  Pluto’s surface never exceeds 63 K (-346 F)

Ø  Pluto’s surface is probably covered by nitrogen, methane and carbon monoxide

Ø  A satellite is a body in orbit around a planet (rather than in its own orbit around the sun)

Origin of Life

Gilmour, I. and M. Sephton. An Introduction to Astrobiology. 2003. Cambridge University Press.

·         Life often defined as a self sustaining chemical system capable of undergoing Darwinian evolution (does not hold true in all cases i.e. donkeys living organisms, but incapable of reproduction, thus incapable of undergoing Darwinian evolution)

·         Carbon can form chemical bonds with many other atoms, allowing a great deal of chemical versatility

·         Carbon can also form a variety of compounds that readily dissolve in liquid water

·         All currently known life utilizes carbon-based organic compounds and water

·         Four most common elements utilized by life on Earth: hydrogen, oxygen, carbon and nitrogen (sulfur and phosphorus also important for life on Earth)

·         Most abundant elements in the Universe (in order): hydrogen, helium, oxygen, neon, nitrogen, carbon, silicon, magnesium, iron, sulfur

·         Most abundant elements on Earth (in order): Oxygen, iron, silicon, magnesium, sulfur, nickel, aluminum, sodium, calcium, phosphorus

·         Water is seemingly essential to life because living systems need a medium in which molecules can dissolve and chemical reactions can take place

·         Water is the major component of living tissue, often accounting for approximately 70% of their mass

·         Hydrogen and oxygen two most abundant elements in the human body

·         Polar solutes dissolve in water, a polar solute. Apolar organic molecules do not readily dissolve in water (like dissolves like)

·         Hydrophilic molecules- soluble, polar molecules that have a high affinity for water

·         Hydrophobic molecules- relatively insoluble, apolar molecules that have a low affinity for water

·         The majority of organic molecules in living systems are large (macromolecules)

·         Four types of macromolecules making up living systems: lipids, carbohydrates, proteins and nucleic acids

·         Lipids (fats and oils) have a hydrophobic end and a hydrophilic end

·         Lipids are poorly soluble in water

·         Lipids are a compact way to store chemical energy and the weak bonds holding them together results in a high degree of flexibility that is useful in membranes

·         Carbohydrates are molecules that have many hydroxyl (-OH) groups attached to them

·         The hydroxyl groups attached to carbohydrates are polar, so carbohydrates are soluble in water

·         Large carbohydrate structures are called polysaccharides, and they are useful energy stores and can also provide structural support

·         Polysaccharides formed via polymerization, a reaction that involves the loss of water

·         There are a number of extraterrestrial environments in which organic matter is produced without the aid of biological processes. These environments include the shells of carbon stars, molecular clouds and the solar nebulae

1.     The atmosphere of carbon stars has more carbon than oxygen

2.     The solar nebula is a disc-shaped cloud of gas and dust left over from the sun’s formation

·         Organic products of extraterrestrial environments would have rained down on Earth around the time of the origin of life, adding to the organic matter synthesized on Earth itself

·         Early organisms unlikely to have used the DNA, RNA and protein based biochemistry common on Earth today- it is more likely that RNA performed the functions of genetic information storage and catalysts

·         Molecular phylogeny indicates that the last common ancestor to all life on Earth was a heat-loving organism similar to the organisms that populate deep sea hydrothermal vents today

The secret of the world
Is written in your eyes
And if I look hard enough
I'm sure to find
Everything's alright
Everything's fine