September 29, 2007 Still waiting on the weather.
Location: Drifting in the pack ice in the Bellingshausen Sea.
Latitude: 70° 31¢ Longitude: 93° 07¢ Air temperature: -11.9 °C (10.6 °F) Relative humidity: 75.1% **Barometric pressure: **946.7 mBar
Antarctic trivia (answer at the end of this journal entry): Are there polar bears in Antarctica?
Another day of waiting out the weather. We awoke yesterday to 60 knot winds and white out conditions. Today is better, but it’s still not safe enough for us to be out on the ice. So we wait, again. We’ve had a lot of practice at that on this cruise! The snow has mostly stopped, but some is still blowing around. We looked out the windows a lot and talked about the weather today…I imagine we’d all be glued to the Weather Channel if we had TV down here! The ice reminds me of the frosting on a cake, not the kind from a can, but the kind I used to make when I was a kid. After you finished beating the egg whites, sugar, and other ingredients together and cooked it the required seven minutes the frosting was thick and glossy. When you frosted the cake you could make curly-cues with the frosting...that’s what the ice looks like! The ice doesn’t exactly form curly-cues, but where pieces of ice stick up from the surface they are "frosted” in beautiful pure white snow.
Snow "frosting” on the ice.
We are waiting to start work on what was originally planned to be a thirty-day drift station. Because of the delays due the fire on September 4, we will probably be here more on the order of three weeks. It is called a "drift” station because even though we’re not covering distance under ship’s power, we are definitely moving, sometimes as fast as we did when breaking through the ice to get here. The ice we are in is not stationary, it moves with the wind and currents. From what I’ve noticed, we drifted as fast as 1.3 knots during the worst of the storm yesterday. We’re moving more slowly now, and in a mostly westward direction. When we arrived here day before yesterday we were at longitude 90° 42¢ W, now we are at 93° 07¢. So, how many miles have we drifted?
First a quick refresher course on latitude and longitude. Think of the Earth as a giant orange. Imaginary parallel lines circle the orange from the top of the orange to the bottom – these are lines of latitude. As you get closer to the poles the length of the lines gets smaller, but no matter where you are, the lines are the same distance apart. Now think of cutting the orange into sections from the top to the bottom. If you draw imaginary lines where you cut, you’ve drawn lines of longitude. All of the lines of longitude meet at the poles. The distance between them increases from a pole until you get to the equator, then decreases again until you get to the opposite pole. Latitude lines are numbered from 90° N to 90° S, with the equator being 0°. Longitude lines are numbered from 0° to 180° E and W.
Ships and airplanes use distances based on latitude and longitude instead of miles or kilometers, so I’ll show you how to do the conversion. One degree of latitude can be divided up into 60 smaller units called minutes – just like one hour can be divided up into 60 minutes. Minutes are indicated by a single quote mark like this ( ¢ ). Each minute of latitude is equal in distance to one nautical mile. So, how is a nautical mile different from a "regular” mile? They are actually very similar – one nautical mile is equal to 1.15 miles, so if there are 60 minutes in a degree, and each minute is 1.15 miles, then there must by 69 miles (60 minutes x 1.15 miles per minute) in a degree of latitude. So, if you travel 3 degrees north or south, you’ve covered 207 miles.
Here’s what we know so far: 1 degree of latitude = 60 minutes of latitude 1 minute of latitude = 1 nautical mile 1 nautical mile = 1.15 miles
So how come this only works for latitude? Remember that lines of latitude are parallel to each other. There is always the same distance between them no matter where you are on Earth. The distance between lines of longitude decreases as you go north or south of the equator. You can use the conversions I described above to convert degrees of longitude to miles if you are fairly close to the equator. The further north or south you go, the more your calculations will be off. There is a conversion factor that you can use that takes into account your latitude. For my location I need to multiply my miles by 0.33 at the end of my calculation. To determine your conversion factor you need to calculate the cosine of your latitude – my latitude is 70° S, and the cosine of 70 is approximately .33, so that’s my conversion factor. If you have no idea what "cosine” means, don’t worry about it; there’s plenty of time for high school math in high school! In the meantime, if you want to do some work with nautical mile calculations find someone who can perform the conversion for the area you want to work with.
Back to the original question…how far have we drifted? By my calculations it’s 2° and 25¢ of longitude (93° 07¢ W minus 90° 42¢ W). That is 145 nautical miles (each degree = 60 nautical miles, each minute equals 1 nautical mile). 145 nautical miles = 167 miles. Multiplying by the conversion factor for this latitude (.33) gives me about 55 miles. So even though we’re not moving, we’re moving!! Lots of math to figure this out, but once you do it a couple of times it’s easy.
That’s it for now, sorry about all the math today. It’s often said that math is the language of science; at least it’s often said by me when my physics students complain about all the math we do in class! Back to looking out the window and talking about the weather…here’s hoping for tomorrow!
**Try this: ** Quick and easy: Our latitude upon arrival at the drift station was 70° 38¢. How far, and in what direction (north or south) have we drifted in terms of latitude?
For older students: Perform the calculations above ending up with kilometers instead of miles. Here are the conversions you need: 1 mile = 1.6 km 1 km = .62 miles
Answer to today’s Antarctic trivia question: Are there polar bears in Antarctica? No, there are no polar bears in Antarctica. Here’s how you can remember where polar bears live…the word Arctic comes from the Greek "arktos” for bear, and the prefx "anti” means opposite, so Antarctic is the opposite of Arctic. So, polar bears in the Arctic, but not in Antarctica.
Marine mammals and sea birds spotted today by Brent: Giant petrel Snow petrel Adelie penguin Emperor penguin