[00:00.00]NARRATOR: Listen to a conversation between a student and his geography professor. [00:04.92]MALE STUDENT: Hi. Professor Brown.
[00:12.25]FEMALE PROFESSOR: Hi. Paul. What can I do for you?
[00:13.94]MALE STUDENT: I have a question about the final exam. [00:15.87]I mean, will it cover everything we've done all term? [00:18.76]Or just what we've been doing since the mid-term exam.
[00:21.70]FEMALE PROFESSOR:Professor: Everything we've done all term.[00:23.31]MALE STUDENT: Oh, boy. [00:24.45]You know, I'm still not too clear about the hydrologic cycle, um ...the transfer of water back and forth between the Earth and the atmosphere ...[00:33.56]I really blew the question about it on the midterm exam. [00:36.72]I wanna do better on the final exam, [00:39.10] but I'm still having trouble with it.
[00:40.71]FEMALE PROFESSOR: Well—um, have you been to the tutoring center?[00:43.79]MALE STUDENT: No, not for geography anyway. [00:46.10]Isn't that just for when you need help with writing ...like an essay or a research paper?[00:50.80]FEMALE PROFESSOR: Oh, no. [00:51.52]You can get tutoring in a lot of subjects. [00:53.83]Some graduate students from this department tutor there.[00:56.89]MALE STUDENT: Um, that's good to know, [00:58.35] but I hardly go there because I have a part-time job. [01:01.04]I never seem to be free when they're open.
[01:03.20]FEMALE PROFESSOR: Well, they'll be extending their hours when final exams begin?[01:06.47]you might try then. [01:07.58]But...since you're here now, can I help you with something?
[01:11.80]MALE STUDENT: Well, the hydrologic cycle ...[01:14.32]I remember we went over a diagram in class ?[01:17.85]and from what I remember ...water changes back and forth from water in lakes and oceans to vapor, and then back to water again when it falls as rain or snow...as precipitation. [01:29.21]It's constantly being recycled, through evaporation and condensation.
[01:33.40]FEMALE PROFESSOR: That's it, basically. [01:35.33] Umm ?so exactly what is it you don't understand?[01:39.55]MALE STUDENT: OK. I guess what I'm really confused about is how the topography of the land—the mountains and valleys and stuff—affect precipitation.[01:47.60]FEMALE PROFESSOR:OK, good question...[01:49.41]Precipitation is influenced by topography, among other things. [01:54.18]Uhh, why don't we talk about lake-effect snow... [01:58.00]It's a phenomenon that occurs anywhere you have a large lake that doesn't freeze, and has cold air flowing over it. Mostly in the Northern Hemisphere.
[02:06.38]MALE STUDENT: Like the Great Lakes in the United States?[02:08.61]FEMALE PROFESSOR: Yes. What happens is that the cold, arctic air blows across the lake from the north in winter, [02:14.93]and as the air crosses the lake, the lower layer is warmed by the lake water, which is much warmer than the arctic air. [02:22.07] And as this layer is warmed and picks up moisture, it becomes lighter than the air above it...
[02:27.92]MALE STUDENT: So it starts to rise, right?
[02:29.79]FEMALE PROFESSOR: Yes. And clouds begin to form. [02:32.89]When the air gets close to the shore, it's slowed down by the land, and starts to pile up. [02:38.94]So it rises even faster, because it has nowhere else to go. That's where topography comes into the picture.
[02:45.74]MALE STUDENT: And then it snows because as the air rises, it cools off and loses its capacity to hold water vapor.[02:52.67]FEMALE PROFESSOR: That's right.
[02:53.83]MALE STUDENT: OK. Thanks. Any chance you'll have this question on the final?
[02:57.55]FEMALE PROFESSOR: I don't know yet... [02:59.53]But you seem to have a handle on it.
托福14天冲刺微信战团