Lecture 4 snow Flashcards
What is a biome
a major geographical area characterized by a particular
type of flora and fauna – primarily determined by CLIMATE (temp and precipitation)
Boreal Regions (definition and 3 types)
- Boreal regions are areas where snow cover affects living organisms
- Taiga – northern coniferous forest
- Tundra – land without trees
- Forest-tundra ecotone – transition between taiga and tundra
The tundra (3)
- Tundra is an ecosystem where tree growth is hindered by low temperatures and short growing seasons
- In other words, these are places so cold and with so few growing days that
trees can’t hardly exist.
-when trees do manage to grow, they take on weird forms—short,
and bush-like
Tundra climate (3)
- Extremely cold
- Desert-like precipitation (very low)
- Large swings in solar radiation
Two (maybe three) types of Tundra
Alpine Tundra and Arctic tundra
Antarctica isn’t really tundra because there isn’t much vegetation
Alpine tundra (5)
- Occurs at high elevations
- Can occur at any latitude, if mountains are high enough
- “above treeline”
- Generally snowy
- Because it can occur at low latitudes, it has ”normal” day
lengths and can have relatively long growing seasons
Arctic Tundra (4)
- Only occurs at high latitudes in the northern hemisphere
- Little precipitation
- Permafrost
- Because it occurs near the north pole, daylight is extremely variable and growing season is 50-60 days
Regions of the Arctic (3)
High Arctic - northern part of tundra
Low Arctic - Southern part of tundra
Subarctic - bellow the tundra
High arctic (4)
- vegetation is short
– bare ground
– less snow or wind
– no winter thaw. Winter desert
Low arctic (3)
– complete vegetation cover
– patches of shrubs
– lots of snow & wind. Can have winter thaw.
Subarctic (2)
– Climatologist: mean temp. >10degrees C for 4 months or less
– Biologist: both forest and permafrost
The Cryosphere (4)
*Portions of the earth where water is in solid form (Frozen ground, Glaciers, Snow cover, Sea ice)
* 2nd largest component of the climate system (after the oceans)
* Influences global energy balance
* Influences ecological functions of northern environment
Frozen ground
- 58% of the land in the Northern Hemisphere freezes seasonally.
-Soil type : light soil freezes faster and stays frozen longer
-lakes and rivers: water warmer than air can heat the ground
-snow: acts as a blanket keeping in heat
-slopes: effect amount of direct sunlight (facing south = more sun)
-wind: If a slope faces into the wind, the ground will lose more heat (through convection)
Frozen ground (7)
- 58% of the land in the Northern Hemisphere freezes seasonally.
-Soil type : light soil freezes faster and stays frozen longer
-lakes and rivers: water warmer than air can heat the ground
-snow: acts as a blanket keeping in heat
-slopes: effect amount of direct sunlight (facing south = more sun)
-wind: If a slope faces into the wind, the ground will lose more heat (through convection) - Plants – In summer, plants keep the soil cooler because they block sunlight from reaching the ground
Permafrost (4)
- is Frozen ground > 2 yr
- Active/organic layer = above permafrost; seasonal thawing & freezing
- Talik = soil or unfrozen ground, year-round (above, within or below permafrost)
*When the active layer thaws, water can’t drain through permafrost = very wet and boggy ground in summer
Permafrost and Plant growth (4)
- Permafrost limits how deep plant roots can grow
- shallow soils do not hold much water = dry quick = less water for plant growth
- water is frozen most of the year and not useable
-Tundra plants have short lifecycles and do not produce a lot of biomass
Formation of ice wedges and polygons (6 steps)
- Cold ground dries & contracts in winter =cracks
- Cracks fill with water in spring
- Freeze when it gets cold, ice expands.
- Forms ice wedges
- Repeat. Wedges grow over time
- soil above the wedges is pushed up, forming ridges =Ice wedge polygons
Formation of thermokarst lakes (2)
*Caused with permafrost thaws and soil collapses
*water fills collapsed area = Irregular surfaces of marshy hollows and small hummocks
*Ponds are darker than surrounding tundra = absorb more heat from the sun, amplify melting
* over time, thread together into beaded streams
Formation of Pingos
Subsurface water can freeze and force frozen ground upward
to form cone-shaped mounds with cores of ice = pingos
Pingos – similar to palsas, but much bigger. Pingos grow
below the active layer, and palsas grow in the active layer
The Albedo Effect
Dark colors absorb radiation, light colors reflect radiation
Arctic amplification (3)
*The Arctic is warming twice as fast as the rest of the planet
* changing from a highly reflective surface to a very dark surface
*Sunlight that would normally be reflected back into space (by sea ice, snow & glaciers) is instead being absorbed by dark surfaces (ocean, land & rock)
Formation of snow pack (2)
Snow pack = change in density of snow
can be destructive or constructive metamorphism
Destructive metamorphism
*destruction of individual grains as snow settles
* Decrease in volume
* Increase in density (reduced space between crystals)
*occurs in new snow
Constructive metamorphism (7)
- Also called temperature gradient metamorphism
- New crystals are formed
- Water vapor rises – moves from warmer area near ground
*Water vapor crystalizes as it hits colder temperatures
*With a greater temperature gradient, more vapor is transferred. - Bottom snow layers becomes loose, less dense, creating crystalline snow = depth hoar
*occurs in Old snow
Depth Hoar (4)
Depth hoar = coarse grains of snow usually found near the soil surface (sugar snow)
– Grains are large and poorly bonded to one another
– Forms subnivian zone
– Destabilizes snow = avalanches
Freeze-melt (3)
meltwater or rain enters the snowpack
* increased vapor migration and freezing lead to large rounded grains
* forms corn snow
How snow cove affects living organisms
- Duration – onset and disappearance of snow cover
- Thickness – How deep the snow is. very important for small mammals
- Hardness – primarily influenced by wind and thaw; force required to collapse the api
- Density – primarily influenced by wind and thaw
Nivean Enviroments
area between fallen snow and gground it rests on
