This is a variety waterfall

Context

This puzzle was written for a summer puzzle picnic in the Boston area, and was intended to be completed on paper outside on clipboards. That being said, feel free to use as many resources as you like while completing it.

Hints

Entering into the grid
The answer to the first clue goes in the section of the column that has the numbers. The answer to the second clue goes in the section of the column right underneath it. The answer to the third clue needs to be split into two parts and then placed in the top and bottom sections. Figuring out how to do that is the trick.
Entering the third clue
This puzzle is called "Heat Rises". Perhaps find a way for heat to rise.

Answers

Answers
The first two clues in each column work like normal. The last clue needs to be split into two parts before being entered into the grid. The first part is a word that is similar to heat, while the second word is one of the words clued by the Additional Clues section. With the "heat" rising and the rest on the bottom, read the grey letters to spell "AN ICE HOTEL".
1. LENTIL/SEMINAL/SAURIAN = SUN + ARIA
2. PANTHERS/GARDEN/LATVIAN = LAVA + TIN
3. SISTINE/VERNE/MEDALIST = MELT + DAIS
4. ALKALI/RADIANT/FAR CRY = FRY + ARC
5. BLOWER/CUBED/BURDENED = BURN + DEED
6. FACET/SPIGOT/OVERNIGHT = OVEN + RIGHT
7. GENOME/CITIES/WASHROOM = WARM + SHOO
8. DANCE/STATUTE/HESITATE = HEAT + SITE
9. PANDEMIC/BELOW/SHOUTED = HOT + SUED
10. CAT/DIALOGUE/MISCALLED = SCALD + MILE