# If I drop a bucket of water from a height, what (if anything) happens to the air pressure on the water?

**URL:** <https://boards.straightdope.com/t/if-i-drop-a-bucket-of-water-from-a-height-what-if-anything-happens-to-the-air-pressure-on-the-water/997259>\
**Category:** Factual Questions\
**Tags:** science-math\
**Created:** [February 7, 2024, 7:22pm UTC](https://boards.straightdope.com/t/if-i-drop-a-bucket-of-water-from-a-height-what-if-anything-happens-to-the-air-pressure-on-the-water/997259 "2024-02-07T19:22:09Z")\
**Posts on this page:** 1\
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**Author:** ![wolfpup](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wolfpup/32/10618_2.png) [@wolfpup](https://boards.straightdope.com/u/wolfpup)\
**Post date:** [February 9, 2024, 2:47pm UTC](https://boards.straightdope.com/t/if-i-drop-a-bucket-of-water-from-a-height-what-if-anything-happens-to-the-air-pressure-on-the-water/997259/25 "2024-02-09T14:47:43Z")

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> [@DSeid](#):
>
> I understood that lower pressure forms behind the lead cyclist dragging on them. A cyclist behind them benefits by being in that lower pressure zone and to a lesser degree benefits the lead rider by reducing the the drag on them. Someone in the middle of a larger peloton gains the most benefit.
> 
> That effect, however I may be misunderstanding it, is big enough for me to be able to notice even at the speeds I was able to hit.

Sure. As a kid on a bicycle cycling on a city street, when I was going upwind it was very helpful to get behind a city bus and be shielded from the wind!

But in the context of this question, we need to ask how important that dynamic pressure effect is to a falling bucket of water. The answer is, hardly at all. Atmospheric pressure at sea level is just a bit less than 15 PSI. The dynamic pressure load from traveling, say, at 30 mph at sea level, as you or I might have been at top speed on our bicycles, is around 0.016 PSI. The negative dynamic pressure would be much less than that. So, IOW, the “draft” effect you’re referencing is completely negligible relative to the static pressure of the atmosphere.

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