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Weather / Meteorology
Atmospheric Layers &Temperature
Weather / Meteorology
Atmospheric Layers &Temperature
• Atmospheric (air) pressure: the force, or weight, of the air
pushing down on a unit area of surface.
• Conduction: the transfer of heat from molecule to molecule.
• Convection: the transfer of heat energy by currents.
• Dew Point: the temperature at which condensation occurs.
• Interface: the boundary between regions having different
properties.
• Isobar: an isoline that connects points of equal atmospheric
pressure on a weather map.
• Isotherm: an isoline that connects points of equal temperature on
a weather map.
• Meteorology: the study of weather.
• Precipitation: (1) the falling of liquid or solid water from clouds;
(2) the process by which dissolved substances come out of
solution to form solids.
Earth’s Atmospheric Layers and Interfaces (p. 14 ESRT)
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Earth is surrounded by a shell of gases called the atmosphere.
Graphs representing temperature, atmospheric (air) pressure, and water vapor concentration
are shown on p. 14 ESRT.
The atmosphere is separated into four different layers. Moving upwards from Earth’s surface
is the troposphere, stratosphere, mesosphere, and the thermosphere.
The different layers are separated from each other at interfaces (boundaries) called “pauses”.
– The tropopause separates the troposphere and the stratosphere
– The stratopause separates the stratosphere and the mesosphere
– The mesopause separates the mesosphere and the thermosphere
The y-axis represents altitude (height above sea level) and is marked in both km and mi.
Make sure you are looking at the correct unit scale for each question!
– The altitude of the tropopause is
about 12 km or 8 mi high
– The altitude of the stratopause is
about 50 km or 31 mi high
– The altitude of the mesopause is
about 80 km or 50 mi high
Earth’s Atmospheric Layers (p. 14 ESRT)
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The y-axis represents altitude (height above sea level) and is marked in both km and mi.
Make sure you are looking at the correct unit scale for each question!
The Temperature Zones graph has temperatures ranging from -100°C to 100°C marked on
the x-axis. Moving upwards from Earth’s surface the air temperature:
– decreases in the troposphere, then
– increases in the stratosphere, then
– decreases in the mesosphere, then
– increases in the thermosphere
The Atmospheric Pressure graph represents air pressures ranging from 1.0 atm at Earth’s
surface to close to 0 atm in the thermosphere. Therefore, as altitude increases,
atmospheric (air) pressure decreases.
The Water Vapor graph represents concentration of water vapor in g/m³. The water vapor
concentration ranges from about 40 g/m³ at Earth’s surface to about 0 g/m³ in the lower
stratosphere. Therefore, as altitude increases, water vapor concentration decreases.
Chemical Composition of the Troposphere (p. 1 ESRT)
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The chemical composition of the Earth’s crust (also called the lithosphere), hydrosphere
(water at Earth’s surface), and troposphere (the lowest layer of earth’s atmosphere) can be
found on p. 1 ESRT.
Data for the hydrosphere and troposphere is given as a percentage by volume.
Data for the crust is given as percentage by mass and by volume.
What is the most abundant element in the troposphere?
– Nitrogen
Heat Energy
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The atmosphere’s main source of heat energy is the sun.
The word INSOLATION (INcoming SOLar radiATION) represents energy from the sun.
Additionally, the atmosphere is heated by:
– Conduction - heat moves from Earth’s surface to the atmosphere when air touches
Earth’s heated surface.
– Coriolis Effect – Earth’s rotation causes friction between Earth’s surface and
atmosphere
– Phase changes – when water changes from solid to liquid to gas and back heat
energy is absorbed or released. (p.1 ESRT)
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Energy is transferred throughout the atmosphere
through the process of convection or convection
currents. Heat rises and cool sinks!
Temperature
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Temperature in the U.S. is generally measured
in °F (Fahrenheit) but can also be measured in
°C (Celsius) or K (Kelvin).
This scale is on p. 13 ESRT
Each line on the Fahrenheit scale is worth 2
°F.
Each line on the Celsius scale is worth 1 °C.
Each line on the Kelvin scale is worth 1 K.
30 °C = 86 °F
330 K = 57 °C
Temperature Patterns on Earth
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Isotherms are isolines that connect points of equal temperature.
Isotherms should never touch or intersect.
In general, warmer temperatures are found near the equator and cooler temperatures
are found near the poles.
Maps of the U.S. will generally have a semi-parallel pattern representing cooler
temperatures to the north and warmer temperatures to the south.
Draw isotherms using a 10°F interval on the map below:
Your work should look similar to this:
Orographic Effect (Mountain Barrier Effect)
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Using the Selected properties of Earth’s Atmosphere Chart (p.14 ESRT) we see that as altitude
increases, air pressure decreases. (There is greater air pressure at Earth’s surface than there
is higher up in the atmosphere)
As air moves up and over a mountain changes occur to the air pressure and temperature.
As air moves up one side of the mountain (the WINDWARD side) the following occurs:
– Rising air has less pressure on it so it expands.
– As air expands, the molecules have more space around and they bump into each other
less often (less molecular collisions)
– Less molecular collisions result in less heat transfer
and the temperature drops.
– As the temperature cools, condensation occurs resulting in
greater humidity (moisture in the air) and clouds and
precipitation (rain, snow) form.
On the other side of the mountain (the LEEWARD side) the air
moves back down towards Earth’s surface and the following
changes occur:
– Sinking air has more pressure on it so the air is compressed
– As air is compressed, more molecular collisions occur
– More molecular collisions cause temperatures to warm
– Warmer air results in evaporation, not condensation,
and the air becomes more arid (dry)
Orographic Effect (Mountain Barrier Effect) Summary
WINDWARD SIDE
air rises
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pressure decreases
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less molecular collisions
↓
less heat (cooler)
↓
condensation results in
clouds and rain (humid)
LEEWARD SIDE
air sinks
↓
pressure increases
↓
more molecular collisions
↓
more heat (warmer)
↓
evaporation results in a
drier (arid) climate