why is there less foam when you pour a drink and tilt the glass than when you don't?

Answer 1

Because there is less agitation when you pour onto the side. A smooth pour makes for less foam. The rougher the pour, the bigger the head.

Answer 2

When you tilt the glass, the drink doesn't have as much of an impact as when you pour it straight into the glass, so not as much carbonation is released, which is what causes the foam. In other words, the longer fall into the bottom of the glass or onto the rest of the drink causes more air bubbles to surface. So while there is less foam when poured against the glass, it will actually be more carbonated and cause more burps.

Answer 3

By pouring along the side of the glass, less CO2 is forced ('bumped') out of suspension. Also, with the glass tilted, there's no surface for the foam to form and dissipate.

Answer 4

When you tilt the glass you reduce the distance the beer has to fall, therefore less distance, less disruption, less foam.

Answer 5

I personally dont think this works, but in general, I'm sure it has to do with the difference in force of the liquid. I think there is only slightly less. Of course I always tilt when I pour....nonetheless!