Why does the water in the toilet bowl

I have asked this question myself, loads of people I mention it to have never noticed.

backdraft

Cor! Some people must just walk around in a little world of their own, eh, Prepared?

Stormy weather is invariably associated with low pressure weather systems.

Can you elaborate on that a bit more please Zola, paying particular attention to the shallowness of the water in my toilet bowl?

There's a vent pipe running from where the waste pipe exits your house to just above the gutter. It gets rid of smells. Perhaps the wind blowing across this has an effect on the water in the S-bend.

MVB- its worrying they havent noticed when using the toilet, If they havent just what else are they missing !!!! LOL, tip of the iceberg!!!

I have also noticed this phenomenon (actualy I have noticed the levels rising and falling) and BillKiller has described my best guess as to what is happening. I think the wind buffets the vent pipe causing the air to push on the water somehow. That said, I'm no plumber.

have you noticed that when it snows It tastes different too .

For me, the toilet bowl water is never deeper when it is windy outside, it's always shallower.

Bernoulli was the first to calculate the pressure effects of moving air.

Attach thread to two golf balls via sellotape

Gusts of wind cause a momentary increase in pressure in the house forcing some water to leave the u-bend......there then appears to be less water in the bowl...

Marvellous Zola! Thank you very much. I shall now refer to this phenomena as Neptue's Retreat.

(Should that be Neptune's Retreat by the way?)

I have used the correct spellin as physicists are notoriously bad a grammar and spelling.

And I made it up.

bad a grammar :D :D

toilets in america are similar to english ones except the bowl is half full of water, theres maybe 1/2 a gallon of water waiting below you, and it can really be splash down.

But you are free to use it from now on without copywrite infirngment.

lol Zola

"In most homes, the drain system has a vertical pipe which leads to an outlet on the roof. This pipe is called a "vent stack". It allows sewage gases to vent to the air outside your house rather than bubbling up through your sink and toilet (ick!), and allows air to pass through the pipes, which ensures that wastewater drains smoothly.

When the wind blows over your house, the air pressure changes because of the "Bernoulli effect". The Bernoulli effect says that pressure becomes lower when flow is faster. It's this effect that sucks loose objects out the car window when you open it while driving; it also creates the lift that allows an airplane to fly. As the wind blows over your house, the Bernoulli effect lowers the pressure at the top of the vent stack. This creates a slight suction throughout the plumbing system, which pulls against the water sitting in the trap in the toilet bowl. As the wind strengthens and weakens, it produces more or less suction, which causes the water in the bowl to slosh."

my thesis on turbulence closure has not been wasted