All five paintings in the show are mounted in MOMA’s second-floor atrium, and you can either spend an hour with each or swivel around to ingest them in a single visual gulp. (Ideally, both.) The first, “Jacob’s Ladder” (1957), would be more appropriately titled “Sherbet Explosion.” The bottom half is a meld of raspberry, pistachio, lavender, and coconut. Out of this confection pop a few wispy purple-gray seed heads. The busyness of the composition below and the emptiness above imply a ground and a sky, which explains why critics often said that Frankenthaler’s work was, in essence, landscape painting. That might not sound like an insult, but it is.