Lecture 2 Flashcards
(61 cards)
T OR F
Climate at the local level is more interesting and complex than the regional climatic type might suggest
T
humidity
pressure
a quantity representing the amount of water vapor in the atmosphere or a gas.
the pressure exerted by the weight of the atmosphere,
climate
characteristic values and seasonal patterns of weather elements that in the long term
Climate is a term that relates to the average state of the earth’s atmosphere and incorporates statistics about temperature, humidity, atmospheric pressure and precipitation for a given region over long periods (i.e., 30 or more years).
It is important to include in the description of climate some indication of ____ and _____ and occasional but significant phenomena, such as a mid-January thaw
variability and extremes
Standard climatological practice is to use the most recent __-year averaging interval to construct climatic normals
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The climate of a location is affected by its: 4
latitude, altitude, terrain conditions and proximity to large bodies of water and their currents
Earth’s climate is driven by energy received from the sun. This energy input, in the form
of ______ radiation, is balanced in the long-term by ________radiation emitted
back into space from earth and its atmosphere.
shortwave
longwave
Earth’s atmosphere is a mixture of different gases. The dominant gases are nitrogen (N2; ___ percent) and
oxygen (O2; __ percent) with the remaining one percent made up of trace gases. The trace gases include relatively small amounts of carbon dioxide (CO2) and other gases (e.g., water vapour (H2O) and methane (CH4)) which absorb longwave radiation and raise the air temperature resulting in what is called the greenhouse effect
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21
These interactions include positive and
negative feedbacks, which magnify (_____ feedbacks) or reduce (______ feedbacks)
the effect of particular actions.
positive
negative
Incoming solar radiation is approximately ____ W/meter 2
longwave(______) radiation back to the atmos can be reabsorbed and or continue into space
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infrared
Geographical factors or ______ work together to
shape particular seasonal and long-term climates. Climatic _____ include: (6)
Geographical factors or controls work together to
shape particular seasonal and long-term climates. Climatic controls include:
1• Latitude (seasonally affects solar radiation and length of day);
2• Continentality (relative position with respect to coasts and continental interior);
3• Elevation above sea level (related to atmospheric lapse rate);
4• Prevailing and seasonal large-scale atmospheric circulation features
(determine the transport of heat and moisture, severe weather and other
phenomena);
5• Regional factors (such as warm or cold ocean currents or presence of mountain
ranges);
6• Local and landscape-scale features that affect the surface energy and water
budgets (forests, wetlands, lakes, glaciers or ice fields).
The earth’s rotational axis is tilted with respect to the plane of its orbit around the sun by approximately _____ degrees (Figure 2-4).
The sun appears to be overhead at different latitudes each day, moving seasonally between the Tropic of _______ (23.5 degrees N) and the Tropic of _______ (23.5 degrees S). The sun never appears directly overhead north of 23.5 degrees N or south of 23.5 degrees S.
23.5
cancer
capricorn
The angle that the sun-earth line makes with respect to the equator is called the _______ of the sun, which ranges from +___ degrees to -___ degrees between the northern hemisphere summer solstice (around ______ 21) and winter solstice (around _____ 22). The sun appears directly overhead at the equator and its declination is zero degrees at the equinoxes (21 March and 22 September).
declination
23.5,23.5
june, december
At local noon the altitude of the sun can be determined by this equation:
Altitude = 90 degrees – (______ - _______)
Altitude = 90 degrees – (Latitude - Declination)
Altitude practice questions:
- Determine the solar noon Sun angle at the following locations and dates:
20°S at an equinox ____________________
The Tropic of Cancer at the June solstice __________________ 40°N at
the December solstice ____________________
The equator at the June solstice ____________________ (4 marks)
The declination of the sun on June 21 is +23.5 degrees so at noon at latitude 60o N, the
sun will be ___ degrees above the horizon.
So Sun Angle for 20oN at an equinox = 90o
-20o
= 70o
On December solstice, declination is -23.5o
, then SA= 90-|lat-(-23.5o)|
So Sun Angle for 40oN at the December solstice = 90o - |40o-(-23.5o)|= 26.5o
On June solstice day, declination is 23.5º, then SA=90º -|lat-(23.5 º)|
So Sun Angle for Tropic of Cancer at the June solstice = 90o
-|23.5o-(23.5 º)|= 90o
So Sun Angle for the equator at the June solstice = 90o-|0-(23.5 º)|= 66.5o
53.5
For example, at 20 degrees, the
irradiance is only / as great as it would be if the sun were overhead. _____ of the
radiation by the atmosphere further reduces incoming energy.
1/3
absorption
continentality
Water has a greater heat capacity than soil or rock, therefore, land surfaces tend to
warm and cool faster than large bodies of water, especially oceans. This means inland
areas generally have higher summer (and daytime) temperatures and lower winter (and
night-time) temperatures than coastal or island locations at the same latitude, although
average yearly temperatures in both locations may be the same. This effect is known as
continentality.
Elevation
As one moves upward in the free atmosphere and away from the earth’s surface, the
temperature usually decreases. On average this decrease, known as the lapse rate, is
approximately 6.5o C per kilometer. Accordingly, one would expect high elevations to
have lower temperatures than lower elevations, all else being equal. Generally, this is a
correct assumption. However, in northern regions there are large regional and seasonal
variations in lapse rates. In large areas of the north, the lapse rate is much less than the
global average. In winter, the temperature lapse over large areas is reversed so the air
above the surface to a height of several kilometers is warmer than it is near the ground.
This phenomenon, known as a temperature inversion, is mainly due to strong radiative
cooling (i.e., longwave radiation emitted from the earth’s surface into the atmosphere) at
the ground when the sun is low or below the horizon. The relationship of temperature to
altitude is more complicated in high terrain than in the free atmosphere. In mountainous
regions no simple rule applies.
On average this decrease, known as the lapse rate, is
approximately ___ degrees C per kilometer
6.5
Explain why there is a latituinal radiant energy imbalance and how that plays into planetary-scale circulation
Energy received from the sun is most concentrated in the lower latitudes (Figure 2-7). In contrast, longwave energy emitted by the earth into space is more evenly distributed with latitude. This means more energy enters the atmosphere at low latitudes than is lost (a
net energy gain), while at high latitudes more is lost than is gained from the sun (net energy loss). This latitudinal radiant energy imbalance results in excessive atmospheric heating in low latitudes, which sets up horizontal pressure gradients that drive the movement of air (and heat) toward polar regions with corresponding movement of cold air toward the equator. The resulting flow is modified by the earth’s rotation, internal atmospheric dynamics and interactions with topography to produce seasonal and longterm wind and pressure patterns that characterize earth’s planetary-scale circulation.
-The Arctic and Antarctic act as heat sinks where more energy is lost from the surface
and atmosphere to space than is gained from the sun. To balance this loss, heat is
imported to high latitudes by the atmosphere through the exchange of air. Picture an
imaginary wall around the Arctic Circle extending to the top of the atmosphere. The
atmospheric circulation flowing through it would consist of equal exchanges of poleward
and equatorward flowing air. This results in a net import of heat to the polar region as
cold air flows south and warm air flows north. This exchange varies seasonally, is
strongest in winter and is focused on specific pathways or trajectories.
General Circulation of Atmos
.5 main cells from North to south
.7 main winds in order from North to south
- Polar Cell
- Ferrel Cell
- between 2 & 3 is subtropical high pressure zone(30 degrees) - Hadley cells
- Ferrel Cell
- Polar Cell
PFHFP= POLAR FRONT HIDES POLAR FRONT
- Polar Front
- Westerlies
- NorthEast Trade winds
- Doldrums
- SouthEast Trade Winds
- Westerlies
- Polar Front
PWNDSWP
Polar Front
winds in the north polar region are shown as mainly from the northeast, converging with the westerlies in a subpolar zone of low pressure, the Polar Front
On average about __ percent of energy that reaches the surface is absorbed at the surface (Table 2-2). About __ percent is reflected back to
space by the surface and atmosphere, which is referred to as the earth’s ____ _____.
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30
planetary albedo
Unlike shortwave
radiation, which passes easily through the atmosphere, nearly all longwave radiation is
absorbed in the atmosphere producing the _________ effect
greenhouse
