Journal Entry

Rangifer tarandus platyrhynchus

Today I visited Dr. Wylie’s 9th grade biology classes at Mill Creek High School in Hoschton, Georgia. Thank you Dr. Wylie and Mill Creek students. You were great!

Mrs. McNeal talking with Mill Creek students about the Svalbard reindeerMrs. McNeal talking with Mill Creek students about the Svalbard reindeer

The topic of the day (and our biology connection) was the Svalbard reindeer. Here are some quick facts:

  • North American caribou and Eurasian reindeer are the same species, Rangifer tarandus.
  • The Svalbard population, Rangifer tarandus platyrhynchus, is an isolated subspecies found only on Svalbard.
  • The Svalbard reindeer is the smallest species of reindeer and exhibits insular dwarfism or reduction in size over many generations when a population’s range is limited, such as on an island.

Compare the two pictures below:

Svalbard reindeer, the smallest subspecies of reindeerSvalbard reindeer, the smallest subspecies of reindeer Strolling reindeer in the Kebnekaise valley, SwedenStrolling reindeer in the Kebnekaise valley, Sweden

Svalbard reindeer have some interesting adaptations as a result of unique environmental pressures, such as:

  • Shorter legs (no natural predators)
  • Smaller size (conserves limited resources)
  • Stockier build (stores lots of fat during winter)
  • Larger stomach (needed to digest poor quality food)
  • Different behaviors and social structure (doesn’t migrate, does not form herds, males do not compete)

The students at Mill Creek had many intriguing questions and insights into this unique animal and its fascinating evolutionary path. I can’t wait to see Svalbard reindeer in person. I will post pictures when I do.

Curious Students Always Have the Best Questions

Thank you, Mill Creek High School for asking great questions for upcoming “Take A Closer Look” journals. You have me thinking and I will be looking for answers to your engaging questions while in Svalbard. Stay tuned to see your questions answered in upcoming journals.

Mill Creek students created engaging "Take a Closer Look" questionsMill Creek students created engaging "Take a Closer Look" questions

Dr. Wylie

Thank you, Dr. Wylie for inviting me to you classroom. Mill Creek students are super kids!

Dr. Wylie and Mrs. McNeal at Mill Creek High School's 9th grade biology classesDr. Wylie and Mrs. McNeal at Mill Creek High School's 9th grade biology classes

Take A Closer Look

Our “Take a Closer Look” question today comes from Gabrielle R. from Mill Creek High School. It is “If the sun doesn’t go down, wouldn’t it be warm in Svalbard and wouldn’t it have no ice?”

Today's "Take a Closer Look" question comes from Gabrielle R. from Mill CreekToday's "Take a Closer Look" question comes from Gabrielle R. Mill Creek

Great question! To be clear, the sun doesn’t set in the summer. In the winter it’s the opposite; the sun doesn’t rise and the arctic circle experiences several months of total darkness. (How depressing.) But to answer your question, imagine shining a flashlight straight up and down on a table. The light “spot” would form a circle. The light energy is focused on the area of the circle. Now imagine tilting the flashlight and shining it on the table at an angle. The light “spot” would spread out and form an oval. The area of the oval would be greater than the area of the circle. With the same amount of light energy spread over a larger area, there is less energy per unit area. When the sun is the source of this light energy, the amount of energy received at different angles is referred to as “insolation”.

Imagine a flashlight shining on a table at different anglesImagine a flashlight shining on a table at different angles

The sun shines straight up and down on the equator during the spring and fall equinoxes and at every location between the Tropic of Cancer and Tropic of Capricorn at some time of the year. But outside of these latitudes, the sun always strikes the Earth at an angle because the Earth is tilted on its axis 23.26º. What this means is that the light received outside of the tropics is more spread out per unit area (like the flashlight) and it hits the Earth at the greatest angle at the poles. So, even though the sun is shining 24 hours a day, the amount of insolation at the poles is less and this contributes to the poles not heating up as much as they otherwise would.

The sun strikes the Tropic of Cancer at 90º on the Summer SolsticeThe sun strikes the Tropic of Cancer at 90º on the Summer Solstice

There is another factor at work here as well: albedo. Albedo measures the reflectivity of a surface. White surfaces reflect light and black surfaces absorb light. What color dominates at the poles? If you said white (snow fields, ice sheets) you are right. Much of the sun’s energy that hits the poles just bounces back off because of the high albedo at the poles. So, low insolation and high albedo combine to reduce the light energy and warming at the poles.

More sunlight is reflected at the poles due to the high albedo of the surface.More sunlight is reflected at the poles due to the high albedo of the surface.

Comments

Mon, 04/28/2014 - 08:56

Peggy McNeal

Neiva and Austin,If snow had a lower albedo (less reflectivity) it would absorb more energy from the sun, just like dirt and mud.

Tue, 04/29/2014 - 10:15

Guest

Can raindeers actually pull santa and his slegh?

Victoria Sanchez , Natalie Pacheco

Mon, 04/21/2014 - 10:10

Guest

Cristian and Dylan
If the sun doesn't go down why is it cold?

Thu, 04/24/2014 - 10:08

Guest

Carson and Delaney period 2If the snow reflects so much light, why is the polar ice caps melting such a problem?

Thu, 04/24/2014 - 10:13

Guest

shakira and matt
why does sunlight reflect off the snow

Thu, 04/24/2014 - 10:16

Guest

This is Haley, Kara, and Alondra from period 2. Are the Svalbard Reindeer a small species because they are endangered?

Thu, 04/24/2014 - 10:17

Guest

This is Sydney and Lexi from period 2. If the sun doesn't rise in winter, so it snows, when the sun doesn't set in summer, wouldn't the sun melt the snow, and then it would be colder because of the albedo?

Fri, 04/25/2014 - 08:41

Peggy McNeal

Sydney and Lexi-I think I understand your question and will attempt to answer and correct some misconceptions.In the polar regions it can potentially snow all year round. There are months in the winter when the sun doesn't rise and months in the summer when the sun doesn't set. However, during the part of the year close to the equinoxes (March and September) the polar regions experience day and night just like the rest of Earth. So yes, the polar regions do experience seasonal changes to the snow cover, with more melting occurring during the summer and accumulation occurring during the winter. However, in many areas the snow does not completely melt even in summer and remains as snow fields or accumulation to glaciers.Albedo increases with snow and ice cover because light reflects more from white surfaces. This reduces energy absorption from the sun. The seasonal changes however are in balance and this maintains the current climate. When there is a long term change (like reduced snow cover over many seasons, years, decades), however the Earth may experience climatic changes due to reduced albedo. Less snow and ice would cause more energy absorption and warming.

Fri, 04/25/2014 - 08:41

Peggy McNeal

Hello Haley, Kara and Alondra,No, the Svalbard reindeer is not endangered. They are small because of "insular dwarfism" which is when a population reduces in size over several generations because of the environmental pressure of being restricted to a small range, such as an island.Good question!

Fri, 04/25/2014 - 09:11

Peggy McNeal

Shakira and Matt-Great question. To fully answer I would have to get into some pretty deep physics. So, let's keep it simple. Different surfaces reflect different amounts of light because of the way they scatter(refract) incoming radiation. When light enters a snow crystal most of the light is refracted inside the crystal, gets bounced around and is bent back toward the observer or the direction from which it came. Since all of the wavelengths of light are refracted/reflected, snow appears white to us and very little light energy is absorbed by the surface. Most of the light is reflected instead.

Fri, 04/25/2014 - 09:11

Peggy McNeal

Hey Carson and Delaney,Because as the polar ice caps melt there is less white. The underlying earth is a darker color. Darker colors absorb more light. Think about when you wear an black shirt versus a white shirt on a hot, sunny day. You will feel cooler in a white shirt because the sun reflects off the white color. You will feel warmer in the black shirt because it will absorb light energy.It works the same with the Earth. Melting ice caps reduce albedo- or the reflectivity at the surface. The underlying Earth absorbs more light energy and warms the planet. Of course, a warming planet is going to cause even more melting of ice caps and this compounds the problem. This is known as positive feedback.Thanks for the question!

Fri, 04/25/2014 - 10:13

Guest

Liliana and Mario period 2 why are reindeer's different size

Fri, 04/25/2014 - 10:16

Guest

This is Neiva and Austin from period 2. Our question is what would happen if the albedo of snow and ice was the same as dirt and mud?