Physical Environment of the Boreal-Arctic Region Part 2 Flashcards
What are 2 implications of northern areas having long, cold winters and short summers in regards to productivity?
- no primary production in winter –> energy stores need to remain in the area
- huge productivity burst in summer –> migrants can capitalize on summer productivity
Insolation=
total amount of solar radiation per unit of time and area
The tilt of the earth’s rotational axis and its spherical shape make the __ ___ ____ of sunlight uneven at diff latitudes
angle of incidence
The average annual temp of northern boreal forests is below __C, and there’s a range of up to __C in seasonal temp extremes.
What results in less extreme variation?
5
100
where oceanic climates prevail (eg eastern canada) b/c the water moderates climate
Temperatures vary __(more/less) in the northern hemisphere where the moderating influence of ___ is less
more
water
more land mass in N hemisphere
___% of incoming sunlight is absorbed by the surface, and most of that is absorbed by ___
45
plants
The amount of solar radiation absorbed by the surface depends on what’s on the surface– ___ absorb the most
plants
amount of solar radiation absorbed by air follows a ___ proportion of the incoming radiation
fixed
light reflected by clouds is ___ in the temperate regions due to dense
higher
clouds
Reflection by the surface s highest at ____, but more in ___ than in ___ because of ___
poles
Antarctica
Arctic
snow
why is snow blindness more of a concern at higher latitudes?
because the sun is coming at you horizontally! due to tilt/ angle of incidence
Historic UV radiation was low in arctic– it is rising b/c of ___
How could this destabilize communities?
ozone depleting
warming
UV can damage DNA & retinas
How does ozone loss differ in Antarctic vs arctic?
Antarctic: almost complete removal of lower-stratospheric ozone currently results in an ozone hole every year
Arctic: ozone loss is highly variable and has until now been much more limited
The ozone layer protects us from ___
___ is important for photosynthesis, and ___ is damaging
UVb
UVa (good)
UVb (bad)
The climate pattern on earth ultimately depends on __ received from the ___ which warms the land and seas
energy
sun
Redistribution of solar energy depends mainly on ____ ____ and ocean ____, which is driven by the ____ of the earth and the position of the continents.
This in turn influences ___ patterns
prevailing winds
currents
rotation
precipitation
Light energy coming in at high latitudes:
- hits earth at an ___, so energy spreads over a large ___
- hit ____ at an angle, so more energy is ___ back to space
angle
surface
atmosphere
reflected
at high latitudes, more energy is ___ than ___, resulting in a net ___.
Near the equator, more energy is ____ than ___, resulting in a net ___
more emitted than gained
cooling
more gained than emitted
warming
climate conditions are divided into 2 subtypes:
1.
2
- maritime: coastal areas where ocean moderates climate= less variation
- continental: much lower precipitation and greater contrast b/w summer and winter
Why would somewhere on Norway’s coast have milder winters than a town in NWT? Note they’re at the same latitude
more ocean warming in Norway than in canada= moderates temps
summer temp in Norway vs NWT is very similar compared to their different winters. Why?
b/c ocean doesn’t have as much of an influence in moderating climates in the summer
- summer temps influenced more by sunlight
Hadley cell is from __ deg to __ deg
Ferrell cell is from ___ deg to ___ deg
Polar cell is from ___ deg to ___ deg
Hadley: 0 to 30
Ferrell: 30 to 60
Polar: 60 to 90
What is the North Atlantic Oscillation (NAO)?
index defined as the anomalous difference b/w the polar low and the subtropical high
- dominant mode of winter climate variability in N Atlantic
- large seesaw in atmospheric mass b/w the subtropical high and polar low
t/f
NAO varies from year to year and does not remain in one phase for longer than a couple of years
false
varies from year to year
tends to remain in one phase for up to several years, which has consequences
A positive NAO system has:
very low L pressure system and a very high H pressure system (greater difference)
a negative NAO system has:
now very low L pressure and not very high H pressure (less difference)
NAO has been mostly ___ recently, which is a major driver of ___ ____
Also, NAO is often linked to ____ dynamics of terrestrial species
positive
climate change
population
Primary productivity on land and water is ___ at high latitudes and ___ with longitude
low
varies
Why are many arctic areas foggy?
Cold air moving over warmer oceanic waters creates fog
Cloud cover is more abundant in northern systems because of the ____
Cloud cover:
__-__% in summer
__-__% in winter
cold
70-90% summer
4-60% winter
Cloud cover:
There’s persistent and extensive ___ cloud layer over the polar ____
- Large scale transportation of relatively mild, __ air into the arctic
stratus
oceans
humid
northern ecosystems receive __-__cm of precipitation per year, which is __ than southern areas
40-100cm
less
Winters are ___in the north, and more than ___ of the annual precipitation falls in the summer
dry
half
How do mountains impact moisture in northern areas of North America and Eurasia?
warm air rises over mtn
air cools as it rises and drops all its moisture on one side
How does winter precipitation impact reindeer?
more moisture in the winter= more deaths because they can’t reach food (lichen covered by too much snow)
Polar vortex= an area of __ pressure located in ___ (almost always present)
low
the arctic
What happens when the polar vortex is strong?
the cold air remains in the north (1 very low L pressure system)
What happens when the polar vortex weakens?
changes the jet stream- it becomes wavier (waves because of relaxation/ destabilization of the system_ and the cold arctic air moves south
The Arctic Oscillation (AO) is linked to the ___ and is driven by similar ___ differences
NAO
pressure
t/f
AO effects are limited just to the arctic
false
represents an important source of variability for the entire N hemisphere
Describe the positive phase of the AO
stable
cold air builds up in north
Low pressure in north- jet stream is consistent with lots of very small waves
describe the negative phase of the AO
destabilized
high pressure in the north
warm air moves north and cold air moves south
- jet stream has a couple of huge waves (reach far south and north)
Impacts of negative phase of AO:
- warm and loss of sea ice in Canada/ greenland
- cold and dry in Norway/ Northern europe
Impacts of positive phase of AO:
cold and more sea ice in N Canada/ Greenland
- warm and wet in N europe
What are the impacts of a positive NAO?
takes warm, moist air from east coast of N America to N Europe
- N Europe gets hot and wet
- drought in S Europe
- warm, moist water over Arctic circle= bad for sea ice
Positive NAO has a __ than usual subtropical high-pressure center and a ___ than normal Icelandic low
stronger
deeper
Negative NAO shows a ___ subtropical high and a ___ icelandic low
What does this mean for the arctic circle?
weak
weak
not as much warm water moving into arctic circle, and more moisture= more ice formation
