greenhouse gases and oxygen Flashcards
what makes earth habitable?
water
greenhouse gases
oxygen
why is water an essential for life?
Due to our habitable zone, the tempertaure allows us to have liquid water. Water can exist at different temperatures.
With hydrogen and oxygen composition, it has the most abundant elements combines.
what states are water in and where?
Water is the only known substance that is present in all 3 physical forms within the range of temperatures.
Water vapour evaporated from the oceans helps transport heat from warm low latitudes to cold high latitudes.
Liquid water contributes to the transport through the ocean currents
Polar regions have both liquid and ice.
how do you reconstruct hydro cycle of the past? (using isotopes)
by tracking the water cycle driven by mass difference. It si easier to get the lightest isotope into water vapour, and hence get an enrichment of the lighter one. When it moves through the atmosphere, the heavy isotope would condense and rain. And get more enrichment in the lighter isotopes. Once you get to high altitudes, it will be highly enriched with the lighter isotopes. Most isotopic fractionation is mass dependent.
how can you quantify different stages in isotopic fractionation?
Can quantify the different stages in isotopic fractionation. Show is enriched in 16O. When ice caps melt, they are enriched with 16O, ocean water becomes 18O rich.
During ice ages- the oceans become richer in the heavier isotope 18, due to ice sheets stealing all the 16O.
why is waters boiling and melting point different compared to other H molecules?
Water- boiling and melting points are very high compared to the other H compounds. This is due to the most electronegative elements form strong polar covalent bonds in hydrogen compounds, and form hydrogen bonds.
Very high electronegativity difference, and hence high boiling points.
what does waters high boiling point result in?
Result of the continual change, it forms ice, melts to water, water evaporates- constant phase transformations as seasons change and latitudes. Very important for temperature regulation.
To melt ice- put in heat. Melting, liquid to vapor- evaporation. When condensing water vapor, you are releasing energy adn heat to the environment.
what happens to energy when you put energy in to change the state?
Energy change stops when you put in energy to change the state- that is when the line goes horizontally, when the water is changing state.
how large is waters latent heat of evaporisation?
Very large latent heat of vaporisation.
what is latent heat of fusion?
Latent heat of fusion- melting/freeing- to do with ice: higher than taht of any substance, other than ammonia.
When water freezes, most of the energy is released to the atmosphere.
When it melts it absorbs large amounts of heat, and ice therefore acts as a thermostat to keep high-latitude water ad atmosphere near freezing point all year.
what is latent heat of evaporisation?
much heat is absorbed in evaportation at low latitudes. Heat transported to higher latitudes by water vapor, to clouds, and then condensation with rain. Releases heat at high latitudes. Thus warming higher latitudes.
why is solid water less dense than liquid water?
Solid water is less dense than liquid water, why ice floats. This is beneficial, as life can survive underneath frozen water as an insulating layer. This is why pipes burst. This is due to hydrogen bonds. This is due to having 4 possible hydrogen bonds, they are locked into place, further apart.
how does water act as a solvent?
Water as a solvent: water dissolves more substances than any other liquid due to polar bond and hydration. In water, ions are hydrate when surrounded by water molecules so as to neutralise their charge.
how different was the young son?
4.5 Ga sun was 30% dimmer than now so not water enough for liquid water
why was the young sun dimmer?
due to the higher number of greenhouse gases, trapping more heat in.
Early atmosphere, very CO2 rich. Sustained heat during Hadean, despite the lower luminosity of the early young sun.
