Lissajous figure alternation back-and-forth coming and going direct tide ebb ebb and flow ebb tide flood flood tide flow flux full tide high tide high water low tide low water lunar tide neap neap tide opposite tide reciprocation refluence reflux rhythmic play rip riptide seesaw seesawing sine wave solar tide spring tide teeter teeter-totter teeter-tottering teetering thalassometer tidal amplitude tidal current tidal current chart tidal flow tidal range tide tide chart tide gate tide gauge tide race tide rip tidewater tideway to-and-fro tottering ups and downs wigwag