ðə wˈɔːɾɚ vˈeɪpɚ ɡɹˈeɪdiənt hˈɛdɪŋ fɹʌmðə tɹˈɑːpɪks tə ðə pˈoʊlz ɡɹˈædʒuːəli bɪkˌʌmz mˈoːɹ ænd mˈoːɹ dᵻplˈiːɾᵻd ʌv ˈeɪtiːn ˈoʊ. snˈoʊ fˈɔːlɪŋ ɪn kˈænədə hɐz mˈʌtʃ lˈɛs ˈeɪtʃ tˈuːhˈʌndɹɪd ˈeɪtiːn ˈoʊ ðɐn ɹˈeɪn ɪn flˈɔːɹɪdə; sˈɪmɪlɚli, snˈoʊ fˈɔːlɪŋ ɪnðə sˈɛntɚɹ ʌv ˈaɪs ʃˈiːts hɐz ɐ lˈaɪɾɚ sˈɪɡnɪtʃɚ ðɐn ðæt æɾ ɪts mˈɑːɹdʒɪnz, sˈɪns hˈɛviɚɹ ˈeɪtiːn ˈoʊ pɹɪsˈɪpᵻtˌeɪts fˈɜːst.
The water vapor gradient heading from the tropics to the poles gradually becomes more and more depleted of 18O. Snow falling in Canada has much less H218O than rain in Florida; similarly, snow falling in the center of ice sheets has a lighter  signature than that at its margins, since heavier 18O precipitates first.