15
votes
Accepted
What is the shortest path between two points on Earth's surface?
If you don't want to do the calculation yourself, you can use an online calculator like the one provided by NOAA.
Alternatively, if you do want to do the calculation yourself you can use the ...
- 24.6k
11
votes
What is the shortest path between two points on Earth's surface?
45E is directly opposite 135W.
It's therefore obvious (hopefully) that the shortest path is straight over the North pole (which is at 90 degrees North). The path takes us round 120 degrees of the ...
- 111
9
votes
Accepted
How do I convert between different east longitude coordinates?
The database with the negative longitude angles is storing longitude as eastings and westings, whereas the other database is storing everything as eastings.
It appears you prefer your data as ...
- 24.6k
8
votes
Accepted
Making clouds for science project
To form a cloud, generally speaking, pressure does not play a significant factor (with the exception of the effect on temperature).
If you want to prove that to yourself, go outside when it is foggy ...
- 8,684
8
votes
Accepted
The fertility of the soil
From this paper from 1958 (page 2),
... gaseous nitrogen of the atmosphere represents a vast store of potential
fertility. It is not directly available to plants. Nitrogen-fixing bacteria, how-
...
- 24.6k
7
votes
The free oxygen (O$_2$) in the atmosphere is largely a result of what process?
You are correct in thinking that oxygen comes from photosynthesis. In fact it is so much associated with photosynthesis, as opposed to any inorganic process, that the presence of oxygen in the ...
- 14.2k
7
votes
Number of tectonic plates
This is primarily an exercise in interpreting a minimalist diagram. Believe me, you will have to learn to read even sketchier diagrams.
That said, the test had the correct answer to the question. ...
- 3,548
6
votes
Take all the CO2 in the atmosphere and put it into a layer on the surface of earth, how thick would the layer be?
Ok, based on the comments above, this is where I am at...
earth's radius is $6371 \text{ km}$
earth is a sphere
There is approximately $3 \cdot 10^{15}$ kg of CO2 in earth's atmosphere
The density ...
- 221
6
votes
Plotting a mineral stability diagram
Remember that you are concerned about stability fields. The lines on your stability diagram are the places where two minerals are in equilibrium. One one side one mineral will be more stable, on the ...
- 4,429
6
votes
Accepted
Interpreting a geological map
1. What is the youngest/oldest rock in the geological history of this map.
Your approach is the right one but isn't the limestone underlain by something? Drawing the AB cross section would be of ...
- 476
6
votes
Why is there a seasonal cycle to the amount of CO2 in the atmosphere?
The magnitude of these seasonal variations differ from location to location. The graph below portrays variations in CO2 levels at Point Barrow Alaska (PTB), La Jolla California (LJO), Mauna Loa ...
- 23.1k
6
votes
Where are the oldest igneous rocks found?
Zircons from Australia at 4.4Ga, and perhaps basalts from a Canadian island at 4.5Ga.
It would interest you to know the quest of Boston University geochemist Matthew Jackson, who is searching for the ...
- 1,339
5
votes
The fertility of the soil
What does 'nitrogen' mean?
Nitrogen might mean gaseous $N_2$. It might also mean compounds, which contain nitrogen, such as nitrate, ammonia and ammonium.
$N_2$
$N_2$ cannot be metabolized by most ...
- 2,661
5
votes
Accepted
A sedimentary rock with only minerals
This is a really bad question, because all three can lack fossils, or all three can have fossils. The definition of "minerals" is also a bit unclear, because fossils are also made out of minerals. I'...
- 23.1k
5
votes
Accepted
How to calculate hydrostatic equilibrium?
I am assuming you are asking for the case of sea level being 200m higher and in isostatic equilibrium. In that case we can make use of Airy's isostasy model: https://en.wikipedia.org/wiki/Isostasy#...
- 413
5
votes
Maps and Faults
There are no dips given, so you have to work by pure geometric deduction. The sediment subcrops on the east side all seem to be roughly parallel to the contours, which suggests near horizontal ...
- 14.2k
5
votes
Accepted
How to graph gravity as a function of depth, given radius and density?
As long as we deal with a spherically symmetric planet, the mass of the shell above you does not influence the observed gravity; the little mass close by exactly cancels the large amounts of mass far ...
- 1,989
5
votes
Number of tectonic plates
There are three plates, because there are two plate boundaries (marked in blue): a convergent margin to the left, and a divergent margin to the right.
Lithospheric plate #2 contains only oceanic ...
- 23.1k
4
votes
Interpreting a geological map
From the dips it is obvious that the stratigraphic structure is a syncline, in which case you correctly deduce that the youngest layered rock is the mudstone. But look carefully. The dips on either ...
- 14.2k
4
votes
Simplest formula of a calcium phosphate mineral?
Yes, you are correct in your calculation. However, the most common hydrated calcium phosphate in nature is indeed hydroxyapatite. Note that industrially, there are several other calcium phosphates (...
- 23.1k
4
votes
Calculating magnetic declination for a non-axial dipole field
Inclination is given by
$$I=\arctan(2\cot\theta)$$
where theta is equal to 90° minus the observer's latitude (in the Northern Hemisphere), therefore
$$I=\arctan(2\cot(90-40))=59,21^\circ$$
To get ...
- 41
4
votes
Accepted
Relative dating of intrusion
It does seem like it's impossible to know unless you have additional information. However, I think there is a hint in there. See this white halo around the intrusion? My guess (and I could be wrong ...
- 23.1k
4
votes
Accepted
To find hardness in Mohrs scale
Although this is a somewhat poorly researched question, I think there is an opportunity to make a nice point here.
First of all, let's look at the Mohs scale:
Talc
Gypsum
Calcite
Fluorite
(fluor)...
- 23.1k
4
votes
Where can I find a shallow-water solver in MATLAB?
You aren't supposed to do link only answers, but that is really all this questions deserves. Did you look on Google? I did.
https://people.sc.fsu.edu/~jburkardt/m_src/shallow_water_1d/...
- 3,366
4
votes
How do I find the horizontal pressure level that divides the atmosphere into 2 layers of equal mass?
I'll answer my own question.
If there is hydrostatic equilibrium, then we have
So, assuming that the surface pressure is p (in this case 1000hPa) and that the atmosphere's top has zero (0) pressure ...
- 129
4
votes
How do I find the horizontal pressure level that divides the atmosphere into 2 layers of equal mass?
Simple?
Only assumption:
hydrostatic relation
$dp = -g \rho dz$
Expanding the RHS yields
$dp = -g \frac{dM}{dV} dz \frac{dA}{dA} = -\frac{g}{dA} dM$
($dA dz \equiv dV$)
So any $\Delta p = c \...
- 438
4
votes
How do I find the horizontal pressure level that divides the atmosphere into 2 layers of equal mass?
I always found this style question interesting as a meteorology graduate teaching assistant, as there often seemed to be a variety of ways to attempt to answer it.
It's also often one of the earlier ...
- 8,713
4
votes
Accepted
How to calculate residence time for an element in a reservoir?
Steady state is when the size of the reservoirs doesn't change with time (because inflow=outflow). The size of each reservoir is the number inside the boxes and the flow rates are the numbers beside ...
- 17.6k
4
votes
Accepted
Relation between Magnitude of Greenhouse Effect and the Concentration of GHGs like $CO_2$
Δ𝐸=133.26+0.044[𝐶𝑂2]
It’s just a numerical coincidence that the 0.044 looks like the molar mass of CO2. That equation gives 0.044 * 380 = 16 W/m2, which is the reduction in surface downwelling IR ...
- 3,940
3
votes
How to graph gravity as a function of depth, given radius and density?
For each point as you descend into your planet you have a balance between gravity due to a solid sphere below you and "counterbalanced" by the gravity due to a hollow sphere of the planet above you. ...
- 822
Only top scored, non community-wiki answers of a minimum length are eligible