The great rain on windshield debate of 2019 (was in interesting discoveries thread)

[Ucinn]

I thought it varied depending how much water was hitting the glass?

Wouldn't one be inclusive of the other? If your going faster I would say more rain will be hitting the windshield

 

[OliverNuther]

Wouldn't one be inclusive of the other? If your going faster I would say more rain will be hitting the windshield

Nope. The amount of rain hitting your windshield depends on the amount of rain falling from the sky. Your speed doesn’t influence that.

 

[Ucinn]

sure it does, you mean when you are sitting at a stoplight, you don't get less rain on your windshield than when you are going 50 MPH?.. sure seems like it to me.

 

[OliverNuther]

sure it does, you mean when you are sitting at a stoplight, you don't get less rain on your windshield than when you are going 50 MPH?.. sure seems like it to me.

The velocity at which the rain impacts your windscreen increases when your car is going faster which is why it seems like it’s raining harder when you’re driving as opposed to sitting at a stoplight.

 

[Ucinn]

The individual raindrops are hitting the windshield faster, and that’s part of it. In addition, more water is hitting the windshield when you’re moving than when you’re not.

That might not be completely obvious, so think about what happens if the rain is falling straight down (i.e., there is no wind). If your windshield were completely horizontal (like a sunroof), it would not matter how fast you were going—the same number of raindrops would hit it every second whether you are moving or stopped.

But now think about what happens if your windshield is perfectly vertical. If you’re stopped, the rain isn’t hitting your windshield at all—remember, in our imaginary world, the raindrops fall exactly straight down. But now, when you move forward, your windshield will hit the raindrops that are falling in front of you.

In real life, windshields are not exactly vertical or exactly horizontal, but somewhere in between. So some rain will hit your windshield even if you are not moving, but more rain will hit it when you are moving.

 

[OliverNuther]

Your windshield is a fixed piece of glass measuring x square metres. Rain falls at a concentration of y drops per square metres. The area of your windscreen remains the same irrespective of your speed. So the volume of water hitting it( y drops/sq mtr) remains the same irrespective of your speed. The only way more water can hit your windshield is if more water falls from the sky.

 

[rocket23]

my head hurts.......

 

[MerlintheMad]

Your windshield is a fixed piece of glass measuring x square metres. Rain falls at a concentration of y drops per square metres. The area of your windscreen remains the same irrespective of your speed. So the volume of water hitting it( y drops/sq mtr) remains the same irrespective of your speed. The only way more water can hit your windshield is if more water falls from the sky.

No. By moving you collect more water. Standing still you get 1 x volume; by moving you get into contact with more rain in a given period of time.

Technically you are correct: only so many raindrops are falling and impacting in a given instant. But the accumulation occurs before the previous rain drops can get off the windshield. So by sitting still you only see the exact number of drops in a given period of time. But for the same period of time while moving you have the rain from the previous periods of time still on the glass, thus the cumulative effect is more water on the windshield.

 

[rocket23]

No. By moving you collect more water. Standing still you get 1 x volume; by moving you get into contact with more rain in a given period of time.

I can testify that when moving it seems like a worse storm than it actually is.....next time you are in the rain driving , remember the amount of rain....then when you stop notice the mere shower/sprinkle than the all out rain that was on your windscreen.

 

[OliverNuther]

No. By moving you collect more water. Standing still you get 1 x volume; by moving you get into contact with more rain in a given period of time.

Technically you are correct: only so many raindrops are falling and impacting in a given instant. But the accumulation occurs before the previous rain drops can get off the windshield. So by sitting still you only see the exact number of drops in a given period of time. But for the same period of time while moving you have the rain from the previous periods of time still on the glass, thus the cumulative effect is more water on the windshield.

Whether you are moving or static you are collecting the same amount of rain. Are you suggesting if you are stopped you magically stop collecting rain after you receive one volume? Your windshield occupies a given amount of space. A fixed amount of rain will fall into that space irrespective of whether it is stationary or moving forward. Your windshield will continue to accumulate that amount even while stopped.

 

[rocket23]

Whether you are moving or static you are collecting the same amount of rain. Are you suggesting if you are stopped you magically stop collecting rain after you receive one volume? Your windshield occupies a given amount of space. A fixed amount of rain will fall into that space irrespective of whether it is stationary or moving forward. Your windshield will continue to accumulate that amount even while stopped.

I'm gonna say no, but not by much. A moving windscreen collects ,gets hit, rain falls on, whatever.......but it will get more water than a car standing still.......but we are not talking a big difference.......good luck trying to figure it out....but to me it seems logical,imo.

 

[eflyguy]

buh-jeezus... mythbusters sorted this out long ago! Go look it up!

Oliver understands...

 

[rocket23]

we got here from wipers?!, I'll pass stand corrected, lets move on,

 

[OliverNuther]

buh-jeezus... mythbusters sorted this out long ago! Go look it up!

Oliver understands...

Yes they did.

Thank you eflyguy.

 

[OliverNuther]

we got here from wipers?!, I'll pass stand corrected, lets move on,

Let’s move on?

From a bloke with 119 posts in his own personal “Dear Diary” thread?

Really?

 

[MerlintheMad]

Whether you are moving or static you are collecting the same amount of rain. Are you suggesting if you are stopped you magically stop collecting rain after you receive one volume? Your windshield occupies a given amount of space. A fixed amount of rain will fall into that space irrespective of whether it is stationary or moving forward. Your windshield will continue to accumulate that amount even while stopped.

Mythbusters be damned if they concluded that there is visibly no difference between moving and standing in a rainstorm. I know what I see, what I have seen for over forty-five years of driving. You can tell the fallaciousness of saying that moving makes no difference by experiencing snow. Impacting snow is much more intrusive on the windshield than simply standing and watching the flakes coat the glass. Yet there are just as many flakes by your reasoning. You move to meet them. Same with rain drops. You are moving to meet more the faster you go. It is as obvious as light compared to darkness, and part of the experienced physical world. Reason away to your hearts content. Play with the "maths" of the phenomenon and let the maths teach you theory bereft of reality.

 

[rocket23]

Mythbusters be damned if they concluded that there is visibly no difference between moving and standing in a rainstorm. I know what I see, what I have seen for over forty-five years of driving. You can tell the fallaciousness of saying that moving makes no difference by experiencing snow. Impacting snow is much more intrusive on the windshield than simply standing and watching the flakes coat the glass. Yet there are just as many flakes by your reasoning. You move to meet them. Same with rain drops. You are moving to meet more the faster you go. It is as obvious as light compared to darkness, and part of the experienced physical world. Reason away to your hearts content. Play with the "math" of the phenomenon and let the math teach you theory bereft of reality.

there fixed it for ya!!

 

[OliverNuther]

Ok let’s try this then. Your windshield is lying on the grass in your backyard. Rainfall is distributed evenly across the yard. You and a friend then pick up the windshield and start moving randomly around the yard. Does more rain land on it now that it is moving? Of course not because rain is falling at the same frequency everywhere you go. You now reinstall the windshield into your car and start driving down the highway. Rainfall is distributed evenly down the highway. Does your windshield attract more rain now that it is moving? Again no.

Impacted snow is more intrusive on your windshield because a) it is denser than rain and b) it is impacting with velocity in your example and thus has greater momentum and is striking with force, packing onto previously fallen snowflakes.

 

[rocket23]

ok, but we do agree that rain hitting a windscreen at 30 mph, splatters, making it seem worse than at a stand still.

 

[moinmoin]

Well, well, well ...
it ain't that simple.
Check this out and draw your own conclusions
Stuff for the yeahs and nays.

Why does it look like the rain hitting my windshield is more ...

https://www.quora.com/Why-does-it-l...s-more-intense-when-I-drive-fast-vs-at-a-stop


classical mechanics - Does more rain strike a vehicle while moving ...

Does more rain strike a vehicle while moving or while stopped (or neither)?


Enjoy!