Lecture 14: Climate and other Niche Axes

Question 1

ecological niche

Answer 1

Combination of physiological tolerances and resource requirements of a species (essentially the species’ place in world, in environment, their behaviours and food)

Question 2

Hutchinsonian niche

Answer 2

Designed by G. Evelyn Hutchinson. Concept that a niche is an n-dimensional hypervolume in which each axis is an ecological factor. Climatic variables are important variables as niche axes.

Question 3

Hadley cell

Answer 3

Make equatorial regions rainy (up to tropic of cancer and tropic of capricorn). As hot air rises (because it is less dense), it cools by 5°-10°C/km, and water vapour condenses and falls as rain near the equator. The air warms again as it falls. This cell affects the equator and subtropics. Just past Hadley cells (+/- 30° latitude) there are dry, high pressure areas).

Question 4

Ferrel cell

Answer 4

Not driven by temperature. Move in opposite direction of polar and hadley cells. Mid latitude segment of earth’s wind circulation. Air flows poleward and eastward near the surface and equatorward and westward near higher altitudes. Transport heat from equator towards poles.

Question 5

Polar cell

Answer 5

Cold, dense air moves from polar regions to about 60°-70° N or S heating up as it moves away from polar regions and rising up and back over. Weakest cell.

Question 6

Temperature is mostly a function of…

Answer 6

latitude

Question 7

Higher latitudes

Answer 7

Are colder; seasonality is mostly a function of temperature (summer and winter)

Question 8

Lower latitudes

Answer 8

are warmer; seasonality is mostly a function of rainfall (dry season and wet season)

Question 9

Rainfall depends on

Answer 9

mostly atmospheric circulation, offshore ocean currents, and rain shadows.

Question 10

Biome

Answer 10

A distinct biological community that has formed in response to a shared physical environment. Determined by temperature, seasonality, rainfall.

Question 11

How does the earth’s tilt produce seasons?

Answer 11

The earth is tilted such that as it loops around the sun the light hits the surface at different angles. At higher altitudes, the lights strikes the earth at a lower angle (thus it is spread over a greater area and is weaker). Near the equator the angle is higher (nearly perpendicular to surface) meaning a more direct area is hit by the light (stronger).

Question 12

Tropic of Cancer

Answer 12

The northern tropic. 23° N ish of equator. Generally hot and dry with two seasons being an extremely hot summer and warm winter. Some easterly coastal regions have excessive rainfall. Much of the land under tropic of cancer is saharan desert. On the June solstice the northern hemisphere is pointed towards the sun and the sun is directly overhead the tropic of cancer.

Question 13

Tropic of Capricorn

Answer 13

The southern tropic. 23° S ish of equator. Contains subsolar point (sun directly overhead) on the December solstice.

Question 14

Where are the tropics found?

Answer 14

Tropic of Capricorn to Tropic of Cancer (23°S - 23°N) including equator.

Question 15

ITCZ

Answer 15

Intertropical Convergence Zone circles the earth generally near the equator where the trade winds (northeast and southeast) meet. Characterized by low pressure, lack of wind, convective activity which generates thunderstorms, Active over continental land masses and less so over bodies of water.

Question 16

Where is the ITCZ situated?

Answer 16

Shifts throughout the year, as the area with most direct sunlight shifts. Warm air is less dense thus creates lower air pressure. ITCZ follows heat. Lags behind the sun’s relative position by about 1 to 2 months. In July and August it is about 5° - 15 ° N (after June 21 solstice (tropic of cancer)) of the equator (but further north over land masses because water has a higher heat capacity than land) and in January over the Atlantic (after December 21 solstice where subsolar point is at capricorn), sits no further north than the equator but extends south over Africa, SA, Asia.

Question 17

Trade Winds

Answer 17

Wind blows from high pressure to low pressure areas. There are areas of high pressure at 30° N and S, and the equator is an area of low pressure so wind is being blown towards equator from north and south. The northeast and southeast trade winds are a result of these winds deflecting from Coriolis effect. Blow to the west from the east.

Question 18

Coriolis effect

Answer 18

Earth’s surface rotates faster at the equator than the poles. Earth’s rotation causes moving bodies at its surface to be deflected. Trade winds from north and south slant westward.

Question 19

Where do you find areas of low pressure and high pressure?

Answer 19

Low pressure zones are a result of rising air (a lot of rainfall). These zones are found where polar and ferrel cells meet and also where the north and south hadley cells meet (rainforest and tropical areas). High pressure zones result from descending air (clear skies, little rain). Found where the ferrel and Hadley cells meet and at the poles (deserts and tundra).

Question 20

How many atmospheric cells are there

Answer 20

Three. Each hemisphere has one of each. Polar cells preside over the poles and hadley cells over the equator. Ferrel cells are found between hadley and act as gear.

Question 21

What direction do winds blow away from the equator towards the north and south pole? Explain why.

Answer 21

Moving away from equator always results in overshoot as land underneath is moving slower as you travel polewards. As winds blow from equator to poles they blow eastward (westerlies).

Question 22

What direction do winds blow towards the equator from the north and south pole? Explain why.

Answer 22

Towards equator moving bodies fall behind so winds from the north pole and south pole deflects to the left. These are the trade winds (northeast and southeast) which converge at the equator

Question 23

Which directions do winds circulate in northern and southern hemisphere?

Answer 23

Low pressure areas suck in air. In the northern hemisphere, the northeast trade winds push west and meet wind flowing from equator that deflects to the right resulting in a circulating cell going counter-clockwise turn. In the southern hemisphere the southeast trade winds also push west and meet the winds coming from equator which deflect to the right resulting in a circular air current spinning clockwise.

Question 24

Wandering albatross

Answer 24

They circumnavigate the northern hemisphere in counterclockwise motion and southern hemisphere in clockwise motion taking advantage of prevailing winds—polar easterlies and westerlies interacting (once they pass 30°N or S). They expend only slightly more energy flying than resting.

Question 25

Describe polar winds

Answer 25

There are also polar easterlies (coming from east going west) as wind from high pressure over polar regions travels towards low pressure areas at high altitudes.

Question 26

Doldrums

Answer 26

ITCZ (where the trade winds converge). Position shifts throughout the year depending on subsolar point. The direct sunlight causes air to heat and rise straight up instead of blowing horizontally -> NO WIND

Question 27

vegetation growth increases with..

Answer 27

moisture and temperature

Question 28

We can predict types of vegetation based off…

Answer 28

combinations of moisture and temperature (latitude is highly indicative of terrestrial biome).

Question 29

Where are deserts found?

Answer 29

30°N and 30°S (high pressure areas where ferrel and hadley cells meet)

Question 30

Why are maritime climates more moderate?

Answer 30

Oceans provide thermal inertia (change temp less readily). They store solar radiation.

Question 31

What affects where atmosphere is moisture laden and where precipitation occurs?

Answer 31

• lots of evaporation from warm bodies of water, low from cool bodies (related to temp)
• prevailing winds
• orographic precipitation (rain shadows air moving over land masses etc)

Question 32

Why is there greater variation in temperature in northern hemisphere?

Answer 32

More landmass, less water to provide thermal inertia

Question 33

Ocean currents transport…

Answer 33

warm water from equator to poles, and cooler water towards equator

Question 34

gulf stream

Answer 34

warm and swift Atlantic ocean current originates in Mexico and stretches to tip of Florida. Influences climate of east coast NA and west coast Europe. Climate of Western and Northern Europe is warmer than it would have been because of the North Atlantic Drift (northern split stream, Canary drift is southern split stream circulates off west coast of Africa).

Question 35

orographic precipitation

Answer 35

warm, moisture laden air is pushed up mountain side, as it rises it cools and rain falls. The dry air falls over leeward side of mountain creating a rain shadow (montane rain shadows, grassy lands east of Rockies).

Question 36

Animal geographic ranges often correspond to…

Answer 36

biomes

Question 37

ecological niche modelling

Answer 37

also called species distribution modelling, uses data from a species current distribution to predict where a species can live (relies on climate data).

Question 38

How is climate change affecting species distribution?

Answer 38

Globe is heating up, organisms are moving polewards at a rate of 6.1 km/decade in 2006 and rate of 16.9 km/decade in 2011

Question 39

What are the biomes (from most productivity to least productivity)?

Answer 39

The seven biomes are: tropical rainforests, temperate forests, taiga (boreal forests), savanna, grasslands, deserts, and tundra.