Download METEOROLOGY

METEOROLOGY
Letter E
i.
Large bodies of water such as oceans, seas, and large lakes affect the climate of
an area. Water heats and cools more slowly than land. Therefore, in the summer, the
coastal regions will stay cooler and in winter warmer. A more moderate climate with a
smaller temperature range is created.
[What about tectonics and climate change? How has the ever-changing geography of
continents affected climate change? Research Wegener and continental drift.]
[what about continents? What are the climates like over
continents?]
ii.
Elevation is the distance above sea level. As you go higher up a mountain, the air
pressure decreases and the gas molecules spread farther and farther apart. Less dense air
holds less heat than dense air, so the farther above sea level you are, the lower the
temperature will be.
Latitude measures how far you are north or south of the equator. Latitude
determines the amount of solar energy received by that region. Regions close to the
equator receive direct rays of the sun and therefore receive more radiant energy and are
warmer. At the areas closer to the poles, the suns rays are at an angle so these areas
receive less radiant energy and are cooler.
[These combine with Milankovich cycles and will change over time. Make sure
you have those concepts down to understand the above.]
iii.
Changes in climate dramatically alter the planet’s
snow- and ice-covered cryosphere. With variations in
the earth’s temperature, thousands of square miles of snow
and ice can accumulate or melt. Changes in snow and ice
cover, in turn, affect air temperature, sea level, ocean
currents, and storm patterns.
[alpine glaciers, Arctic sea ice, landbased ice caps are not defined! How are
they being affected by temperature change?]
Snow and ice help keep the earth cool by reflecting
between 60% and 90% of the solar energy that shines on
them back into space. Reduction of snow cover and sea ice
may lead to increased warming, as more solar energy is
absorbed. [what is the connection between this and
“albedo” of Earth?]
Climate models suggest that global warming will be felt
most acutely in the polar regions, particularly the Arctic.
Researchers have already observed many changes in the
Arctic, including the warmest temperatures in the last 400
years, an earlier melting of ice on lakes and rivers, and a
decline in the extent of spring and summer sea ice.
Studying the cryosphere also gives scientists valuable
insights into how and why the earth’s climate has changed
in the past, how it is currently changing, and what may lie
ahead. Ice at the poles and in glaciers contains detailed
records of past climate, including bubbles that capture
samples of the earth’s ancient atmosphere. By examining
ice cores—cylinders of ice taken from deep below the
surface—scientists gather data dating back hundreds of
thousands of years.
[what is this a graph of?]
[what is this a graph of?]
iv.
The topography, or features of the land also influences the climate. The
amount of precipitation in a region is affected by mountain ranges in that area.
Mountains cause air to rise. Rising air becomes less dense allowing the
condensation of water. Precipitaion occurs. Air moving down the other side of
the mountain becomes more dense. Sinking air does not produce precipitation.
The leeward side, or side facing away from the wind, receives much less
precipitation.
[Be able to point out some specific areas of the world that show this effect. Like the
Rockies or the Andes. How are the climates on windward/leeward side affected?
Which sides are windward and leeward?]
[For the min/max stuff below, what is the main idea? What is the point of
tracking min/max temperature and not just average temperature?]
v.
Mean maximum temperature (°C)
The average daily maximum air temperature, for each month and as an
annual statistic, calculated over all years of record.
Highest temperature (°C)
The highest (by month and overall) maximum air temperature observed at
the site.
Lowest maximum temperature (°C)
The lowest (by month and overall) maximum air temperature observed at
the site.
Decile 1 maximum (or minimum) temperature (°C)
Monthly or annual decile 1 (10th percentile) of maximum or minimum air
temperature. The annual decile value must be calculated from yearly data, and
cannot be obtained by adding together the monthly deciles. Decile values are
used to give an indication of the spread of the observations over the period of
record; in this case, daily observations within a month. To determine decile
1of a series of observations, they are first arranged in order from lowest to
highest, and then divided into 10 equal groups. Decile 1 is the value at the top
of the 1st grouping. Over the long term about one day in ten can be expected
to have a (maximum or minimum) temperature below the decile 1 value.
Records from land stations and ships indicate that the global mean surface
temperature warmed by between 1.0 and 1.7°F since 1850 (see Figure 1).
These records indicate a near level trend in temperatures from 1880 to about
1910, a rise to 1945, a slight decline to about 1975, and a rise to present
(NRC, 2006). The Intergovernmental Panel on Climate Change (IPCC)
concluded in 2007 that warming of the climate system is now “unequivocal,”
based on observations of increases in global average air and ocean
temperatures, widespread melting of snow and ice, and rising global average
sea level.
# Since the mid 1970s, the average surface temperature has warmed about
1°F.
# The Earth’s surface is currently warming at a rate of about 0.32ºF/decade or
3.2°F/century.
# The eight warmest years on record (since 1850) have all occurred since
1998, with the warmest year being 2005
* The warming trend is seen in both daily maximum and minimum
temperatures, with minimum temperatures increasing at a faster rate than
maximum temperatures.
* Land areas have tended to warm faster than ocean areas and the winter
months have warmed faster than summer months.
* Widespread reductions in the number of days below freezing occurred
during the latter half of the 20th century in the United States as well as most
land areas of the Northern Hemisphere and areas of the Southern Hemisphere.
* Average temperatures in the Arctic have increased at almost twice the
global rate in the past 100 years.
The IPCC has concluded that most of the observed warming in global average
surface temperature that has occurred since the mid-20th century is very likely
a result of human activities (IPCC, 2007). During the first half of the last
century, there was likely less human impact on the observed warming, and
natural variations, such as changes in the amount of radiation received from
the sun, likely played a more significant role.
Observations compiled by NOAA’s National Climatic Data Center indicate
that over the past century, temperatures rose across the contiguous United
States at an average rate of 0.11°F per decade (1.1°F per century). Average
temperatures rose at an increased rate of 0.56°F per decade from 1979 to
2005. The most recent eight-, nine-, and ten-year periods were the warmest on
record.
Warming occurred throughout most of the U.S., with all but three of the
eleven climate regions showing an increase of more than 1°F since 1901. The
greatest temperature increase occurred in Alaska (3.3°F per century). The
Southeast experienced a very slight cooling trend over the entire period (0.04°F per century), but shows warming since 1979.
Practice Reading these maps.