Q18 - In the troposphere, the lowest

[joyce.hau]

I drew a little diagram for this one. The first thing I felt puzzled about was why temperatures seemed to be warmer over the poles than over the equator. Am I not getting the correct meaning of the word "ranges"? Are they referring to a range of -50 degrees WITHIN the troposphere over the poles and -85 degrees WITHIN the troposphere over the equator? Anyway I did not take that into account while answering, so could that be part of the problem?

Secondly, the right answer D says that "the temp any point at the top of the stratosphere is at least as great as the temp at the top of the troposphere directly beneath that point."

This was my diagram with some provisional numbers (excuse its crudeness):
____________________________________________
(strato) (top:warmer) -30

(bottom:colder)_-50 over the poles
____________________________________________
(topo) (top: colder) -50 over the poles

(bottom: warmer) -30
_____________________________________________

So how can it be that -30 is "at least as great as" the temperature at the top of the troposphere?? (What does that even mean?)

[aileenann]

Great question! I can tell you are hashing this out in detail just as you should be. This kind of lawyerly (i.e. detailed) thinking is going to pay off.

Regarding your first question, I read it the same way you did, that oddly enough, the poles have a higher temperature than the equator at the top of that particular layer. Even if it doesn't make sense to you given your outside knowledge, ignore that - this is a test of reasoning not knowledge!

I think if you take a look at (D) you can see that it's true for one reason only, which is that once the stratosphere starts, the temperature starts going up again. Therefore, wherever it is (on that same line, as it were, going from Earth up), once it hits the stratosphere it'll start going up again. So say we finish the troposphere at a particular point that is -70, the coldest it can be in the stratosphere is -70, and likely it will be getting warmer, so the temperature will be going up.

This all in turn means that any point above that minimum ice cold troposphere point is going to be warmer - hence the "at least as" language.

I hope that helps. Let me know if you still have questions!

[mchuynh]

I am a bit lost, I was left with answer choices B and D.. why isn't it D?

[aileenann]

Hello there,

You are not confused - the answer is (D)! Perhaps you are asking why it's (D) and not (B)?

I think my post above explains why the answer is (D). Even though (D) has kind of technical or unintuitive language, all it says is that in the stratosphere - that upper layer where the temperature increases as you go further up, any temperature you have will be at least as high as the top of the troposphere. That makes sense because the top of the troposphere is the bottom of the stratosphere, which means it's the lowest temperature in the stratosphere. I should have indicated in my first post that the diagram the student poster gave is not correct. Really in that diagram the strato top should be warmer than the strato bottom, so it could be, say, 70, but it could not be 30 as is indicated on that diagram.

As for why (B) is not the correct answer, let's take a look. (B) is making a statement about temperatures at the top of the stratosphere near the poles as opposed to over the equator. This answer choice might be tempting because we know that the troposphere is warmer over the poles than over the equator *but* we'd be making a logical mistake to assume that this same pattern holds for the stratosphere. They didn't tell us that it does, so we don't want to make that assumption.

Does that make sense? Please let me know if I haven't answered your question or if you have another one

[kmewmewblue]

I cannot even get to the point what you guys are talking about.
First of all, I don't know what "one" is.
"the temperature decreases as one progresses straight upward."
"and the temperature stops decreasing and instead increases as one progresses straight upward through the stratosphere."

Is it amosphere that progresses straight upward? What!?

Sorry, I am totally confused.

[demetri.blaisdell]

I'll step in here to answer your question, knewmeblue. In the stimulus, "one" just means "you." It's a slightly old-fashioned way to use the word. So you can read it as "the temperature decreases as you progress straight upward" and "instead increases as you progress straight upward."

For the troposphere, they are saying "as you go up, the temperature goes down." For the stratosphere, the opposite is true.

When you read it like that, does it make more sense? Take a look at the answers above and let me know if you still have any questions.

Demetri

[kmewmewblue]

Dear demetri,

Thank you so much for answering my silly question.

Now it makes sense, and I realized "aileenann" was explaining "as you go up." But without your explanation, I wouldn't understand anyways....

Thank you again

[Raiderblue17]

can someone link a diagram... Im confused by temperature going up, does that mean the number incrases I.E. from -50 Celsius to -51 celsius, or does it mean it incrases such as heat from -50 C to -49C

A diagram of this all would be great... I didn't understand the first posters one at all

[demetri.blaisdell]

An increase in temperature means that it will get hotter (e.g. from -50 to -30). I can't really come up with a better diagram than the first one. Think of it in terms of heat and see if it makes more sense. Let me know if you have any more questions.

Demetri

[legalrabbithole]

I actually made up new numbers to help me wrap my head around this question.

First, you need to know that the stratosphere is above the troposphere.

S
----
T

Technicalities aside, the stem basically says that in the tropo, it's hot at the bottom and cold at the top. In the strato, it's the opposite. In the strato, t's cold at the bottom and hot at the top.

S (top) hot, 90
S (bottom) cold, -10
------------------
T (top) cold, -10
T (bottom) hot, 90

(D) is saying that the temperature at S(top) is going to be equal to or greater than the temp at T(top).

In other words if S(top) is around 90 degrees and T(top) is around -10 degrees, then of course, S(top) is going to be as hot or hotter than T(top).

[jlz1202]

Hi aileenann, I think I understand your explanation of why choosing D instead of B. Initially I narrowed down to B and D, I couldn't find anything wrong of both and pick B out of no reason. When I review I find I have make a unwarrant assumption in B: I presume the degree of temperature increase in the entire Stratosphere is even: since above pole, stratosphere starts with -50 and above equator starts with -85, temperature increases with altitude therefore I think at the temperature of highest point of pole stratosphere would be higher than that of equator. But I ignore the following situation: although both point in stratosphere, temperature increases with altitude,
somewhere around equator, the increase could be: 10 degree/meter while around pole: 5 degree/meter, so if the total height in stratosphere is 1000 meter, then in the highest point, the temperature above pole would be: -50 + 10*1000, way higher than temperature of highest point of equator -85 + 5*1000.

My lesson is never think outside of what stimulus mentioned in must be true question.

Could you please confirm whether my understanding above is correct?

Thanks a lot!

[demetri.blaisdell]

jlz1202,

That's exactly it. The question is asking for what must be true. You can't 100% guarantee (B). In fact, think about the fact that ultraviolet rays from the sun are warming the ozone. Does it seem likely that the poles receive enough sunlight to be warmer than the equator.

(D) compares the atmosphere above the same area, so it's a valid, 100% provable comparison.

Good work on this one.

Demetri

[calebrosser]

I have a problem with this question in a way that is different from the concerns raised previously.

I realize fully, as I did at the time of my selection, that it would be an assumption to assume that the temperature traits over the poles and equator and their relation to each other would continue to exist in the stratosphere.

However, I was apprehenisve about D because of the use of "at least as great as" In this sense, is great supposed to mean warmer as opposed to colder? Because I construed "great" to mean an absolute value. So, for example, if the temperature at the top of the stratosphere would be +13 and the temperature at the top of the troposphere directly beneath this point would be -900000, then the logic would hold, but surely the latter temperature is "greater."

So, is my understanding that I was wrong because of my misinterpretation of the word "great" correct?

Thanks

[zana.nanic]

OOOooEnd of Troposphere and beginning of stratosphere O O OO

Every O in the Sphere is bigger or equal the O at the top/end of the Tsphere. O= degrees


The negative sign might be condusing, this is way is super easy to see it.

[daniel]

I made a little diagram for this as well, but the diagram is only useful in terms of confirming the correct answer choice. Below is how I eliminated the other four answer choices:

(A) Unsupported comparison: We have no information in the stimulus to make any inference about the thickness of anything, anywhere.

(B) Unsupported comparison: We don't know what temperature the top of the stratosphere is for different locations. We only know the temperatures for the top of the troposphere.

(C) Unsupported comparison: We don't have any information about the temperature in the middle part of the stratosphere.

(D) This must be true based on the information presented in the stimulus.

(E) Out of scope. Ozone layer? Impact to temperatures in troposphere? What?! We're only told that the stratosphere is warmed by ozone (presumably, a lack of ozone would result in a lack of heat generated in the stratosphere, which is the opposite of what the answer choice says), but we don't have enough information to infer how depletion of ozone layer would impact troposphere.