上弦或下弦 meaning in English

quarter

Neap tides : tides of small range occur when the moon is at its first or last quarter
小潮：出现在每个月上弦或下弦时期，潮差特别小的潮汐。
On days around neap tides when the moon is at its first or last quarter , however , tidal ranges become small and sometimes only one high and one low tides are observed
每个月的上弦或下弦，潮差却变得很小，这个时期叫做小潮。有时在小潮期间，每日只有一个涨潮和退潮。
On days around neap tides when the moon is at its first or last quarter , however , tidal ranges become small and sometimes only one high and one low tides are observed
每个月的上弦或下弦，潮差却变得很小，这个时期叫做小潮。有时在小潮期间，每日只有一个涨潮和退潮。