Glasgow have one hand on the 1872 Cup after a 16-6 victory at Scotstoun last Saturday, and another win in Edinburgh would see them regain top spot ahead of Ospreys' clash with Scarlets on Saturday.
And Townsend admits he is expecting much more of a free-scoring game this time around thanks to the wide pitch at BT Murrayfield.
"It's not huge but the extra width definitely makes a difference," he said. "You are playing on the biggest pitch you can play on, so it does mean there is more turf to defend.
"Factors that we always look at before games are the condition of the pitch, the dimension of the pitch and the weather.
"You can play the rugby you want to play more easily if the weather is better. If it stays dry and cold, that would be good.
"But, with the bigger pitch, defences might be spread and that can mean holes open up. They might show you the outside so you go there, but it is harder ball to win, so there might be more turnovers."
Both side's defences came out on top in a brutal first-leg encounter, and - despite being pleased with the discipline Glasgow showed under pressure - Townsend urged his men to produce quicker ball this time around.
He added: "Physicality is a big part of our game. Big tackles are what you want to see. We were pleased with our defence and I thought Edinburgh defended well too but, from my perspective, the physicality was really good.
"We know we have to keep improving defensively, in the contact area and create quick ball. Another aspect that pleased me was that there were no yellow cards, so, in terms of the macho element, I felt we kept our discipline very well."
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