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1) Differences in pressure between the air and the ocean cause carbon dioxide to be exchanged and 2) algae and phytoplankton absorb carbon dioxide.


The ocean can absorb carbon dioxide (#CO_2#) in 2 ways: diffusion from the atmosphere and through photosynthesis in plankton and algae.


Carbon dioxide moves between the atmosphere and the ocean by molecular diffusion: a difference between #CO_2# pressure in the atmosphere and ocean causes #CO_2# to be exchanged (source). The #CO_2# moves from the air to the water, when the atmospheric pressure of #CO_2# is higher. The #CO_2# is dissolved in the ocean because it is soluble.

The solubility of carbon dioxide varies based on salinity and temperature of the water and there is a finite amount that the water can absorb. The colder the water, the more #CO_2# can be dissolved.

The solubility of #CO_2# in water is demonstrated in the video below.

Another way in which the ocean absorbs #CO_2# is through some of its lifeforms. Phytoplankton and algae both photosynthesize in the ocean. They both consume #CO_2# using sunlight and release #O_2#.

For more information:
The Ocean Carbon Cycle
Carbon Dioxide in the Ocean and Atmosphere
The Marine Carbon Cycle Video


It can't.


The temperature can never go below the dew point. The dew point is the temperature that 100% relative humidity is reached, based on the amount of water vapour in the air. That means that once the temperature drops to that point, the air cannot hold any more water vapour so condensation occurs. If condensation occurs then the amount of water vapour in the air will drop. If the amount of water vapour in the air drops the dew point will drop.

enter image source here


Looking at the above chart, if we have 20 grams of water vapour in1 kilogram of air at 30 degrees, we are at about 75% relative humidity. If the temperature drops 5 degrees we are at 100% relative humidity. That means that the dew point was 25 degrees. At that point condensation will occur. If the temperature drops another 5 degrees (now at 20 C), we will lose about 5 grams of water vapour as liquid water in that kilogram of air. The relative humidity stays at 100% but the dew point will have dropped.

Long story short, the dew point can equal the dry bulb, but at 100% relative humidity if the dry bulb drops so does the dew point. The highest the dew point can ever be is the dry bulb temperature.


It takes a day for the Earth to rotate about its axis, but there are several definitions of a day.


The period it takes the Earth to rotate about its axis is called a day. There are however several definitions of a day which are all slightly different. It all depend on what you measure the time relative to. Also, due to orbital effects successive days are not the same length.

A Mean Sidereal Day is one complete rotation of the Earth relative to the fixed stars - 23h 56m 4.1s

A Mean Solar Day is 24h or 86,400s which is what clocks measure.

A Solar Day as measured by a sundial is between 24h-20s and
24h+30s. The Solar Day length various continuously from day to day. The Solar Day and Mean Solar Day are only the same length on 15 April, 13 June, 1 September and 25 December.

The reason why the Solar Day changes from day to day is due to the Earth's orbit being elliptical and the axial tilt.

The orbital eccentricity component is the orange line on the diagram. It have zeros at the apses.

The obliquity component, due to the axial tilt, is the green line which has zeros at the equinoxes and solstices.

The difference between the Mean Solar Day and the Actual Solar Day is described by the Equation of Time which is the blue line in the diagram and is the sum of the two components. The vertical axis is minutes difference between clock noon and solar noon.
enter image source here


The many round depressions on the moon's surface are called craters.


Craters are formed by the impact of meteors striking the moon's surface. Asteroids (meteors) are traveling very fast through space; when those asteroids impact a surface they carry a lot of kinetic energy and the impact is very explosive. www.chamaeleon-observatory-onjala.de

Craters of asteroid/meteor impacts can also be observed on Earth; however, since the earth has an atmosphere most small asteroids burn up before reaching the earth's surface. Only large asteroids survive to impact the earth's surface such (see image below). Since the moon has no atmosphere, even the smallest asteroids may impact the surface leaving craters.


It has had more time to crystallise


Intrusive igneous rocks are as you described, magma that sits deep in the crust and slowly crystallises.

The main control on crystal growth is time, if a lava is erupted onto the Earth's surface then it has little time to crystallise and therefore the grains are smaller. This could be something like a basalt (which is an extrusive igneous rock):


But if you leave the magma in the crust and give it time to crystallise, then the grains will be much bigger like that of a granite:



Water vapor is released by volcanos. It is possible that the earliest water vapor came from volcanos.


There has always been oxygen in the atmosphere of the earth. Water vapor breaks apart into Hydrogen gas and Oxygen gas under the radiation from the sun. The water vapor must have been in the atmosphere from the earliest beginnings of the earth, as evidenced by the presence of Oxygen in the earliest rocks.

Volcanos are known to release large volumes of water along with the volcanic ash and lava. It is possible that volcanos were responsible for the earliest occurrence of water.

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