Key PointsGoogle Cloud’s operating margin jumped from 23.7% to 36.2% in a year as quarterly revenue passed $30 billion.More than 55% of Google Cloud's backlog is expected to become revenue within 24 months.Heavy spending, negative free cash flow of $9.1 billion, and rented computing capacity could squeeze margins in the near term.Motley Fool Issues Rare "Total Conviction" Buy Alert › Alphabet (NASDAQ: GOOGL) (NASDAQ: GOOG) is arguably best known…