Neap tide

Definition: A tide that occurs when the difference between high and low tide is least; the lowest level of high tide. Neap tide comes twice a month, in the first and third quarters of the moon.
external image image001.jpg

biogrophy:
http://www.math.nus.edu.sg/aslaksen/gem-projects/hm/0102-1-phase/SUNMOONONTIDES_files/image001.jpg
http://www.enchantedlearning.com/subjects/astronomy/moon/Tides.shtml