What is most likely to happen when Earths' orbit intersects the tail of a comet?
If the Earth passes through a comet's tail, a bright meteor shower composed of multiple meteor trails would form in the sky but most meteors would burn up completely before any debris hits the ground.
A comet's tail is composed of a trail of volatile gases, dust, and rock particles dislodged from the comet's body by the heat of the sun (evaporation) and by the solar wind.
If the Earth passes through a comet's tail, it will pass through this thinly scattered debris trail and its atmosphere will capture some of the comet's particles. The comet's gases will just blend in with Earth's atmospheric gases but the dust and rock particles will be slowed down by collisions with the atmosphere's molecules and eventually fall to the Earth's surface.
The dust and rock particles may have high velocity so that friction with the atmosphere will abrade them and raise their temperature so that they streak down as meteors from the sky. If they are large enough, the meteors could form a bright visible trail of incandescent vaporized particles containing flame and smoke. If many meteors happen in a short amount of time, it forms a meteor shower.
Most grain-sized meteors are burned up totally without hitting the ground but some falling rocks are large enough survive until they explode as a "bolide" or to hit the ground as a "meteorite."