At these latitudes, the sun's rays are weak 在这样的高纬度 阳光的强度非常微弱

130. But the mother has given her cubs the best possible start in life.
     但是母亲已经给了它们一个最好的开端
131. The geese will continue grazing the tundra
     雪雁还将一直在苔原上吃草
132. until the summer ends and they're forced to head south for the winter.
     直到夏天结束 它们才会被迫南迁过冬
133. At these latitudes, the sun's rays are weak
     在这样的高纬度 阳光的强度非常微弱
134. and grass can only grow here for a few months a year.
     这里的草儿只有几个月的生长期
135. But further south, summers are longer and the grasslands flourish.
     但是在更远的南边 夏天的时间更长,草原更加茂盛
136. The prairies of North America.
     北美大草原

来自《行星地球 第一季 第七集 Planet Earth S01E07 伟大草原》第 133 行