#03-004: Longitude

Earth with meridians of longitude
(Wikipedia)

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Note: Lily and Antonio complete the conversation they started in Lessons #03-002 and #03-003, about the earth's "grid" of lines.

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Get Ready: Which hemisphere do you live in, north or south? East or west?

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Lily, from China, and Antonio, from Spain, finish their conversation about geography in the Common Room of their dorm.

Lily: Hey, Antonio. Let's do longitude.

Antonio: <rubbing his hands together> Ready!

Lily: So, latitude is measured by the horizontal lines on the globe--

Antonio: Parallels.

Lily: Right. And the lines of longitude that run north to south are called "meridians."

Antonio: Hey, that sounds familiar.

Lily: Yeah, the word is used in a few expressions. For example, the "Prime Meridian" is the 0-degree line that runs through Greenwich, England.

Antonio: I remember now. Every thing to the east of that, to the 180 line, is the Eastern Hemisphere.

Lily: Yes, and to the west is the Western Hemisphere.

Antonio: If the Prime Meridian is in England, then isn't most of Europe in the "east"?

Lily: Technically, I guess you're right.

Antonio: OK. Anyway, I think I heard "meridian" somewhere else...

Lily: Well, you know "a.m." and "p.m." don't you?

Antonio: Naturally. Before and after noon on a 12-hour clock.

Lily: Yeah. Actually, "noon" is when the sun is over head, on (or near) the same meridian where you're located. The "a" in "a.m." means "ante," or before, and the "p" of "p.m." means "post"--

Antonio: After!

Lily: Exactly. So "a.m." and "p.m." are "ante meridiem" and "post meridiem," before and after noon.

Antonio: "MeridiEM?"

Lily: Don't worry, it's a Latin thing.

Antonio: OK. Here's a toughie: Is 12 noon really 12 a.m. or 12 p.m.?

Lily: Actually, it's neither. If a.m. is BEFORE noon, and p.m. is AFTER, then noon itself can't be before OR after.

Antonio: But still...

Lily: But nuthin'. Just stick with "12 noon" and you'll be OK.

Antonio: And "12 midnight" for the other one?

Lily: That's best.

NOTES:

• The "12-hour clock" is used in many English-speaking parts of the world, where we say "1 p.m." rather than "13:00." The clock used in some other places is called a "24-hour clock."
• When Antonio says, "MeridiEM?" he wants to know why it isn't "meridian." When Lily says, "it's a Latin thing," she means that the change has to do with the rules of Latin grammar.
• Lily says "But nuthin'" because she doesn't think Antonio's objections are important; she stops him before he goes on. It's a little rude, but might be done between friends.

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Read more: https://en.wikipedia.org/wiki/Longitude

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Practice: Match the term to its definition below:

1. do longitude
2. rubbing his hands together
3. the globe
4. technically
5. toughie
6. stick with

1. study or talk about [something]
2. a difficult question
3. continue to do something a certain way
4. a gesture of excitement or enthusiasm
5. the information may be true, but it's not really very important.
6. the earth, or a 3-D model of it

Answers are in the first comment below.

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Submitted to the Shenzhen Daily for January 12, 2012

This lesson received 169 visits on my old site between January, 2012, and July, 2021.