Causes of tides 2

Spring tides are those with higher high tides and lower low tides than normal, or a greater range of tide. They occur when the sun and the new moon, or the sun and the full moon are in straight line with the earth exerting a larger than normal gravitational force, and therefore causing a greater than usual tidal range.
Neap tides are tides with lower high tides and higher low tides than normal – in other words – a smaller range of tide. These occur when the moon is in a quarter phase and the sun, moon and earth form a right triangle. Because the sun is not in a straight line with the earth, the gravitational pull of the sun counteracts the gravitational pull of the moon and as a result, the tidal range is unusually small.