Spring tide are tides with the greatest tidal range. Despite their name, spring tides don’t just
occur in the spring; they occur throughout the year whenever the Moon is in a new-moon
or full-moon phase, or about every 14 days.
Here is a link to see these tides in motion: http://oceanservice.noaa.gov/education/
kits/tides/media/tide06a_450.gifLicense: GNU-FDL)
Figure 14.13: Spring tides occur when the Earth, the Sun, and the Moon are aligned,
increasing the gravitational pull on the oceans. Sometimes, the Sun and Moon are on
opposite sides of the Earth while at other times, they are on the same side. ( 29 )
Neap tidesare tides that have the smallest tidal range, and occur when the Earth, the
Moon, and the Sun form a 90oangle (Figure14.14). They occur exactly halfway between
the spring tides, when the Moon is at first or last quarter. This happens because the Moon’s
high tide occurs in the same place as the Sun’s low tide and the Moon’s low tide is added to
by the Sun’s high tide.