Over the past two days or in

Question

Please look at the following and tell me what is the difference between them

The rainfall activity has gone down in the past two days.
The rainfall activity has gone down over the past two days.
The rainfall activity has gone down for the past two days.
The rainfall activity has gone down during the past two days.

Now do all the sentences mean that the rainfall activity is still going down at present? i.e., at the moment of uttering these words? Also was the rainfall going down continuously during the entire two day period? Or were there any chances that it didn't happen continuously?

Thank you

Not what you're asking about but "rainfall activity" means exactly the same as "rainfall" so the extra word just makes the sentence longer and harder to read. — David Richerby, Aug 02 '16 at 13:36
@DavidRicherby thanks. Would you want to address the question? — Policewala, Aug 02 '16 at 13:38
#2 and #4 mean exactly the same (a progressive reduction over a 48-hour period). #1 could apply if the amount of rain suddenly dropped 2 days ago, and has remained at exactly the same (lower) level since then. #3 implies you measured the amount of rainfall yesterday and today, and on each occasion it was less than the preceding day. Subtle differences, but in context they could be significant. None of them imply anything about whether there may be further reduction in the future (i.e. - whether it's ongoing). — FumbleFingers, Aug 02 '16 at 13:50
@FumbleFingers, I have not understood the explanation for #1. If the rainfall has remained the same, then why have we used gone down in #1? What does gone gone down in #1 signify? To me your explanation for #2, #3, and #4 look the same. On any occasion, in all the three, the rainfall would be less than previous day. Also, by "In the past two days mean today and yesterday, right? Thank you — Policewala, Aug 02 '16 at 14:48
Per @David's comment, "rainfall activity" isn't a very natural English expression anyway, but it's also a bit uncertain what going down = reduction** means (less hours of rainfall, or less total precipitation?). So let's switch to The price of butter in my local supermarket* has gone down in the past two days.* That would normally be understood to mean that the price was reduced two days ago, and has remained at the same (lower) price since then. In that context, *during* or *over* would be unlikely, since they imply multiple reductions over a period of time. — FumbleFingers, Aug 02 '16 at 15:13
(Note that the past two days could mean today and yesterday or yesterday and the day before, depending on context.) — FumbleFingers, Aug 02 '16 at 15:25
@FumbleFingers I don't think that "the price... has gone down in the past two days" means that it happened two days ago. It just means that the price today is less than it was on Sunday. (And, presumably, the speaker either doesn't know exactly when the decrease or decreases happened, or doesn't think it's important enough to mention.) — David Richerby, Aug 02 '16 at 15:43
@David: There's plenty of scope for subtle semantic distinctions that may be either more or less likely with specific prepositions of time. So *in* is more likely to mean on one occasion, sometime* with that period, whereas during* is more likely to mean *continuously / repeatedly, over the entire period*. — FumbleFingers, Aug 02 '16 at 16:03
But what if I were to replace the above present perfect with simple past? What would the difference then be?

The rainfall activity went down over the past two days.

The rainfall activity has gone down over the past two days. — Policewala, Aug 03 '16 at 03:28

score 4 · Accepted Answer · answered Aug 02 '16 at 17:10

As @DavidRicherby said, just "rainfall" would be more natural than "rainfall activity."

Sentence 1 – in

The rainfall has gone down in the past two days.

This means that, at some point in the previous two days, the volume of rainfall has decreased. There is no indication of whether it decreased gradually over the two days or not.

Sentence 2 – over

The rainfall has gone down over the past two days.

This sentence has at least two meanings that I can see:

That the amount of rain that is falling has, over the past two days, decreased; or
That, in comparison to the volume of rain that fell in some other time frame, the volume of rain that fell over the past two days was less.

Here's an example for the second meaning:

On Monday and Tuesday we measured 15mm of rainfall. On Wednesday and Thursday we measured 10mm of rainfall. Today is Friday, so the rainfall has gone down over the past two days.

Sentence 3 – for

The rainfall has gone down for the past two days.

This has a similar meaning, but to me it has different connotations. It means that the volume of rainfall has gradually decreased, but it also implies that multiple measurements were made over the course of the two days and at each measurement the volume had decreased.

Sentence 4 – during

The rainfall has gone down during the past two days.

This sentence doesn't sound natural to me. It would certainly be understood, but it doesn't sound natural. However, this may just be a dialect difference between British and American English. If we use Google Ngram Viewer, we can see that "during the past two" used to be significantly more common in American English than it was in British English:

American English:

British English:

Using over is the safe option, since in both cases during is declining in usage. However, it does appear that during is correct.

Thank you fro your detailed response. Isn't it said that 'in the past two days' or 'in the past week' mean refers to a period of time stretching backwards two days / one week, from today. But if we take it to mean yesterday(Thursday) and the day before yesterday(Wednesday), then the period doesn't start from today. And this violates this condition. Please shed some light and tell me where I am erring. Also, would the meaning change if we replace the above present perfect sentences with simple past? — Policewala, Aug 03 '16 at 13:30
Two days back from Friday is Wednesday, in the same way that 3-2=1 and not 2. If someone said "for/in/over/during the past two days" to me, I would not interpret that as including today unless it was said late at night. As for your second question, here is one of the questions on ELL that ask about present perfect vs simple. If this doesn't clear it up for you, I'd recommend creating a separate question. — LMS, Aug 03 '16 at 21:35

Over the past two days or in

1 Answers1

Sentence 1 – in

Sentence 2 – over

Sentence 3 – for

Sentence 4 – during