Lecture 13 & 14 Flashcards
Does water or land have a greater heat capacity
Water
Can solar radiation penetrate further into land or water, therefore spreading energy at a greater depth
Water
Is latent or sensible heat dominant for water
Latent
Is Q* larger over water or land?
Water- has a lower albedo
Effectiveness of QE and QS mean that Qh …
is small
During the day, is land or sea warmer?
Land
At night, is land or sea warmer?
Sea
What is the marine thermal characteristics similar to?
The soil temperature profile
What is the marine thermal characteristics similar to?
The soil temperature profile
Why is there no sea breeze in the morning?
Sun still rising, no temperature differences between land and water, so no pressure differences mean no circulation
What breeze develops during the day?
The sea breeze
What breeze develops at night?
The land breeze
What kind of conditions are conducive to SB-LB occurrence?
Strong thermal difference between land and sea
high SW radiation input (little clouds), weak synoptic scale winds
What kind of conditions are conducive to SB-LB occurrence?
Strong thermal difference between land and sea
high SW radiation input (little clouds), weak synoptic scale winds
Characteristics of sea breezes - temperate climates eg South Island
typical windspeeds of 2 to 5 ms-1
typical inland extent of 30-50 km
characteristics of sea breezes - tropical climates
> 300 km inland extent
the sea breeze front
associated with the development of cumulus cloud, may be sufficient uplift to lead to precipitation
direction of breeze
initially perpendicular, but influenced by Earth’s rotation / Coriolis force so may become parallel with coast by late afternoon
Implications of sea breezes
Relief from high temperatures, disperse pollution
Lake breeze cause
Land will warm faster than the lake during the day so onshore lake breezes may result
Generally, the active surface is elevated so that zero plane displacement =
d=2/3h
Does albedo of a stand decrease higher or lower in the canopy?
Decreases with height
Effects on SW radiation in vegetation
Albedo, shading, skyview factor
Effects on LW radiation in vegetation
the larger skyview factor, the more LW radiation is retained.
Effects of vegetation on energy balance
Q*=QH+QE+QS+QP+QA
What is Qp
biochemical energy storage due to photosynthesis
The energy balance of vegetated surfaces- QE
most dominant flux
The energy balance of vegetated surfaces- QH
flux is reversed because high evaporation keeps the crop cool
The energy balance of vegetated surfaces- QG
no QG - ground is shaded so heat storage is soil is small
The energy balance of vegetated surfaces- QS
relatively small heat stored inside crop
Is the forest a heat sink at day or night
Day
Is the forest a heat source at day or night
Night
Why is it not always possible to generalise vegetation effects on energy balance?
Diversity of vegetation species and vegetation structures
Stand architecture
Vertical differences
Orientation of principal exchange surfaces
Precipitation in forests: stem flow
Water drained along leaves, branches to tree stem
Precipitation in forests: canopy drip
Water directed to the edge of tree
Precipitation in forests: interception
Water held in the canopy
Precipitation in forest: water extracted from…
the atmosphere
Vegetation effects on wind speed
Wind speed approaches zero well above the ground surface
Why are wind and turbulence in canopies important?
Momentum transfer - wind load & wind throw
Land atmosphere interactions - global biogeochemical cycles, energy balance, water use and evapotranspiration
Dispersion - dispersion of pollen, forest fires, air pollution
