Chapter 12. Meteorology
Recommended Post : 【Earth Science】 Earth Science Table of Contents
1. Composition of the Atmosphere
2. Phenomena Due to Water Vapor
5. Climate
1. Composition of the Atmosphere
⑴ Components of the Atmosphere
① Emission of carbon dioxide from residential heating accounts for 1/5 of carbon dioxide emissions from power facilities.
② 70-80% of oxygen in the atmosphere is produced by aquatic plants.
⑵ Evolution of the Atmosphere
① Nitrogen : Its reactivity has been low and its quantity has remained constant throughout Earth’s history.
② Carbon dioxide : Initially, there was more carbon dioxide than nitrogen, but it gradually decreased due to the formation of calcium carbonate and dissolution in water.
③ Oxygen : Increased gradually with the emergence of photosynthetic organisms. The oxygen revolution occurred about 2.1 billion years ago.
⑶ Structure of the Atmosphere
① Troposphere
② Stratosphere
③ Mesosphere
⑷ Anomalous Propagation of Sound Waves
2. Phenomena Due to Water Vapor
⑴ Three States of Water
① Latent Heat : Heat exchanged during a change of state without a temperature change.
② Evaporation : Conversion of water to water vapor, absorbs latent heat.
③ Condensation : Conversion of water vapor to water, releases latent heat.
④ Melting : Conversion of ice to water, absorbs latent heat.
⑤ Freezing : Conversion of water to ice, releases latent heat.
⑥ Water Cycle : The movement of water on Earth’s surface and between the surface and the atmosphere through state changes.
⑵ Temperature
⑶ Humidity
① Condensation : When the amount of water vapor exceeds a certain limit, water droplets form.
② Nuclei for Condensation and Freezing
○ Condensation Nuclei : Hygroscopic substances, etc.
○ Ice Nuclei : Volcanic ash, soot, etc.
○ Without condensation or ice nuclei, even in supersaturated conditions, condensation may not occur, creating a state of supersaturation.
③ Causes of Condensation (Cooling)
○ Contact Cooling : Cooling that occurs when air contacts a cold surface or cold water.
○ Mixing Cooling : Cooling that results from the mixing of warm and cold air.
○ Radiative Cooling : Cooling due to nocturnal radiative heat loss.
○ Adiabatic Cooling : Cooling due to the expansion of air as it rises.
○ Adiabatic cooling has the greatest cooling effect.
④ Vapor Pressure
○ Vapor Pressure : The pressure exerted by water vapor in the atmosphere, proportional to the amount of water vapor.
○ Saturation Vapor Pressure : Vapor pressure of saturated water vapor in the atmosphere, proportional to temperature.
⑤ Relative Humidity : The amount of water vapor in the atmosphere relative to its saturation point at the current temperature (measured in %).
○ A larger difference between temperature and dew point results in lower relative humidity.
○ Relative humidity is 100% when temperature and dew point are equal.
○ Relative Humidity = Current Vapor Pressure ÷ Saturation Vapor Pressure × 100 (%)
⑥ Absolute Humidity : The amount of water vapor in 1 m³ of natural air (moist air) expressed in g.
⑦ Dew Point Temperature : The temperature at which air would need to be cooled at constant pressure to reach saturation, causing condensation to form.
○ Dew point temperature is the temperature where vapor pressure equals saturation vapor pressure.
○ The dew point temperature is the same for air masses with equal vapor pressure.
⑧ Hygrometer
○ Hair Hygrometer
○ Dry and Wet Bulb Hygrometer
○ Adiabatic Saturation Temperature
Figure 1. Adiabatic Saturation Temperature
○ Wet-Bulb Temperature
Figure 2. Wet-Bulb Temperature
⑷ Adiabatic Changes, Adiabatic Lapse Rate
① Adiabatic Changes : Temperature changes in a rising or sinking air mass solely due to changes in volume.
○ Adiabatic Expansion
○ As air rises, its volume expands due to decreased surrounding pressure, resulting in cooling.
○ Work is done against external air, causing the air mass to cool.
○ Adiabatic Compression
○ As air sinks, its volume compresses due to increased surrounding pressure, resulting in warming.
○ Work is done by external air on the sinking air mass, causing it to warm.
② Adiabatic Lapse Rate : The rate of temperature change in an air mass as it rises or sinks adiabatically.
○ Dry Adiabatic Lapse Rate : The rate of temperature change for unsaturated air as it rises adiabatically.
○ 1 ℃ / 100 m
○ Moist Adiabatic Lapse Rate : The rate of temperature change for saturated air as it rises adiabatically.
○ Due to latent heat release from condensation during ascent, it is lower than the dry adiabatic lapse rate.
○ 0.5 ℃ / 100 m
○ Dew-Point Lapse Rate : The rate of dew point temperature change for unsaturated air as it rises.
○ Unsaturated Air: 0.2 ℃ / 100 m
○ Saturated Air: 0.5 ℃ / 100 m
○ (Note) Formation of ice begins at 0 ℃.
○ Example
Figure 3. Example of Adiabatic Lapse Rate
○ Temperature at 800 m in ascent: 30 - 1 × 8 = 22 ℃
○ Temperature at 2,000 m in ascent: 22 - 0.5 × 12 = 16 ℃
○ Temperature at point B in descent: 16 + 1 × 20 = 36 ℃
⑸ Clouds
① Cloud Formation
○ Cloud : Water vapor in the air undergoes adiabatic cooling, leading to the presence of water droplets or ice crystals suspended in the sky.
○ Cloud Formation Process : Air rising → Volume expansion → Adiabatic cooling → Cloud formation
○ Growth of Ice Crystals : Ice crystals adhere to supercooled water droplets due to higher saturation vapor pressure of water droplets compared to ice.
○ Below 0 ℃, supercooled water droplets coexist with ice crystals.
○ Air in the cloud is unsaturated with respect to supercooled water droplets.
○ Air in the cloud is supersaturated with respect to ice crystals.
② Level of Condensation
○ As unsaturated air rises
○ The air mass cools at a rate of 1 ℃ / 100 m due to the dry adiabatic lapse rate, and the dew point decreases at a rate of 0.2 ℃ / 100 m.
○ Consider the change along the temperature line.
○ As the air mass rises, the difference between temperature and dew point decreases until they become equal at the condensation level, where relative humidity reaches 100%, leading to cloud formation.
○ Condensation Level (m) = 125 × (Surface Temperature - Dew Point)
③ Classification Based on Cloud Shape
○ Stratiform Clouds : When the atmosphere is unstable
○ Flat base and rounded top
○ Develops vertically due to upward motion; atmospheric instability is present
○ Associated with shower-type precipitation
○ Cumuliform Clouds : When the atmosphere is stable
○ Spreads horizontally
○ Associated with continuous and light rain
④ Classification Based on Cloud Altitude
○ High Clouds : Altitude of 6 ~ 13 km
○ Cirrus Clouds
○ Cirrostratus Clouds
○ Cirrocumulus Clouds
○ Middle Clouds : Altitude of 2 ~ 6 km
○ Altostratus Clouds
○ Altocumulus Clouds
○ Low Clouds : Surface to an altitude of 2 km
○ Stratus Clouds
○ Stratocumulus Clouds
○ Nimbostratus Clouds
○ Vertically Developing Clouds : Develop vertically regardless of altitude, including cumulus and cumulonimbus clouds
⑹ Rain, Snow
① Types of Precipitation
○ Convective Precipitation : Caused by air rising due to convection
○ Orographic Precipitation : Caused by air rising over mountains
○ Cyclonic Precipitation : Caused by air rising around low-pressure centers
○ Frontal Precipitation : Caused by air rising along a front
② Thunderstorms : Composed of initial stage, mature stage, and dissipating stage
○ Initial Stage : Characterized by updrafts, resulting in large, thick clouds
○ Mature Stage : Thunder and lightning are prominent. Strong updrafts and downdrafts coexist.
○ Dissipating Stage
⑺ Fog
① Type 1. Fog due to Vapor Supply
○ Evaporation Fog
○ Advection Fog
② Type 2. Fog due to Cooling
○ Radiation Fog
○ Advection Fog
○ Upslope Fog
⑻ Smog : Smoke + Fog
① London-Type Smog
○ Formed due to sulfur dioxide emissions
② LA-Type Smog
○ Generated by nitrogen oxides
○ Ozone generated near the surface
○ Can occur on clear days with strong ultraviolet radiation
3. Atmospheric Motion
⑴ Measurement of atmospheric pressure
⑵ Measurement of winds
① Wind Speed : Wind speed is usually observed using a Robinson anemometer or a Dines pressure-tube anemometer
② Wind direction
⑶ Radiative motion of heat
① Solar radiation
② Attenuation of solar radiation by the Earth’s atmosphere
③ Albedo
⑷ Atmospheric stability
Figure. 4. Atmospheric stability
① Adiabatic lapse rate : The degree to which the temperature decreases due to adiabatic action as an air mass rises
○ Adiabatic lapse rate line : Temperature variation with altitude obtained by applying adiabatic lapse rate
② Temperature lapse rate : The degree to which the temperature decreases due to external factors
○ Temperature change line : Temperature variation with altitude obtained by applying temperature lapse rate
③ Stable : Adiabatic lapse rate > Temperature lapse rate
○ Surface ~ Specific altitude : Adiabatic lapse rate line > Temperature change line
○ Specific altitude ~ : Adiabatic lapse rate line < Temperature change line
○ Surface ~ Specific altitude : Air mass rises
○ Specific altitude ~ : Air mass descends
○ Phenomenon : Rising or descending air returns to its original position (specific altitude)
○ When the atmosphere is stable, damage increases during heavy fine dust or fog
④ Unstable : Adiabatic lapse rate < Temperature lapse rate
○ Surface ~ Specific altitude : Adiabatic lapse rate line < Temperature change line
○ Specific altitude ~ : Adiabatic lapse rate line > Temperature change line
○ Surface ~ Specific altitude : Air mass descends
○ Specific altitude ~ : Air mass rises
○ Air masses rapidly move in both directions centered around a specific altitude
⑤ Neutral : Adiabatic lapse rate = Temperature lapse rate
○ When adiabatic lapse rate line < temperature change line across all altitudes: Air mass descends gradually
○ When adiabatic lapse rate line > temperature change line across all altitudes: Air mass rises gradually
⑥ Conditionally unstable : Dry adiabatic lapse rate > Temperature lapse rate > Moist adiabatic lapse rate
○ Unsaturated air : Stable
○ Saturated air : Unstable
⑦ Foehn Effect (Foehn, Föhn) : Also known as “naksaepung” or “high valley wind”
○ Point 1. Surface ~ Initial condensation point : Dry adiabatic change. Increase in relative humidity. Decrease in absolute humidity
○ Point 2. Initial condensation point ~ Mountain peak : Moist adiabatic change. Constant relative humidity. Decrease in absolute humidity
○ Point 3. Mountain peak ~ Beyond the mountain surface : Hot and dry. Dry adiabatic change. Decrease in relative humidity. Increase in absolute humidity
○ Adiabatic lapse rate example ( Figure. 3. ) for reference
⑧ Elevated inversion layer
○ Inversion layer : Atmosphere region where temperature increases with altitude
○ Type 1. Elevated inversion layer : Formed near the surface due to fog, etc.
○ Forms on clear, calm nights due to strong radiative cooling at the surface
○ Cloud cover inhibits radiative cooling and makes it harder for inversion layers to form
○ Case 1. Adiabatic lapse rate line always below temperature change line: All air masses descend to the surface
○ Case 2. Adiabatic lapse rate line initially higher than temperature change line but then decreases: Very stable, and air moves to the intersection of adiabatic lapse rate and temperature change line
○ Type 2. Orographic inversion layer : Warm air passes over cold air
○ Type 3. Subsidence inversion layer : Formed by subsiding air in areas of high pressure in the upper atmosphere
○ Type 4. Frontal inversion layer
⑸ Forces Generating Winds
① Pressure gradient force
② Coriolis force
③ Centripetal force
④ Frictional force : Only significant within 1 km from the surface
⑹ Winds Following Pressure Gradients
① Geostrophic wind
○ Wind that results from a balance between the pressure gradient force and the Coriolis force
○ Wind blows when isobars are straight and more than 1 km above the surface: No friction or centripetal force
○ Wind speed increases at lower latitudes : (1/ρ) × ΔP/ΔH = 2vΩ sin φ
② Gradient wind
○ Wind that results from a balance between the pressure gradient force, Coriolis force, and centripetal force
○ Wind blows when isobars are curved and more than 1 km above the surface
○ High-pressure gradient wind
○ Wind direction : Clockwise
○ Coriolis force - Pressure gradient force = Centripetal force
○ Coriolis force = Pressure gradient force + Centripetal force, making it faster than the geostrophic wind
○ Low-pressure gradient wind
○ Wind direction : Counterclockwise
○ Pressure gradient force - Coriolis force = Centripetal force
○ Coriolis force = Pressure gradient force - Centripetal force, making it slower than the geostrophic wind
③ Surface winds
○ Atmospheric pressure gradient force, Coriolis force, and friction are involved : Centripetal force may or may not be involved
○ Wind direction : Diagonally upward to the right of the atmospheric pressure gradient force direction
○ Slope : Angle formed between isobars and surface winds. Larger at lower altitudes with stronger friction
○ High-pressure zonal wind : Divergent in a clockwise direction. Associated with subsidence
○ Low-pressure zonal wind : Convergent in a counterclockwise direction. Associated with ascent
⑺ Wind Patterns due to Atmospheric Circulation
① Atmospheric circulation scale
Figure. 5. Atmospheric circulation patterns according to spatial and temporal scales
○ Larger spatial scale implies larger temporal scale
○ Larger scale results in smaller vertical/horizontal scales
② General circulation : Arises due to latitude-based energy imbalance
Figure. 6. General circulation
A : Hadley cell, B : Ferrell cell, Others : Polar cell
Figure. 7. Wind speeds due to near-surface winds by general circulation
○ Equatorial Doldrums (0°)
○ Trade winds (0° ~ 30°) : Easterlies
○ Subtropical high-pressure zone (30°)
○ Westerlies (30° ~ 60°)
○ Subpolar low-pressure zone (60°)
○ Polar easterlies (60° ~ 90°) : Easterlies
③ Land Breeze
④ Monsoon Winds
○ Causes are the same as those of land breezes
○ Monsoon winds are not influenced by the Coriolis force
○ Winter winds are faster than summer winds
⑤ Mountain and Valley Breezes
○ Upslope breeze
○ Equilibrium breeze
○ Upslope mountain breeze
⑥ Westerly Wave
○ Cause : Latitude-based temperature differences, Coriolis force
○ Role : Resolving latitude-based energy imbalances, generating subtropical low-pressure zones and migratory high-pressure zones
○ Strong westerly winds exist between mid-latitudes and the North Pole due to turbulence waves caused by Earth’s rotation
Figure. 8. Westerly Wave
○ Interpretation of the figure
○ Right, down, left, up correspond to east, west, south, north respectively
○ The part rising to the north is called the pressure ridge, the part rising to the south is called the pressure trough
○ A : Corresponds to the pressure ridge. Fast-moving ( ∵ High-pressure gradient wind)
○ B : Rapid speed at A causes descending current at B, turning the surface into high pressure (migratory high-pressure zone)
○ C : Corresponds to the pressure trough. Slow-moving (∵ Low-pressure gradient wind)
○ D : Slow speed at C causes ascending current at D, turning the surface into low pressure (subtropical low-pressure zone). Typhoons can develop here
○ Jet stream : Fastest portion of westerly wind at mid-latitudes. Located at the tropopause
○ Type 1. Subtropical jet stream : Found at latitude 30°
○ Type 2. Polar front jet stream : Found at latitude 60°. Faster than subtropical jet stream
○ Jet stream becomes stronger and expands north-south with stronger pressure and temperature differences between mid-latitudes and the North Pole
○ Jet stream is faster in winter than summer : Winter has a greater temperature difference at different latitudes
○ Jet stream moves southward in winter and northward in summer
○ Weakening of the jet stream can bring cold air from the North Pole to mid-latitudes, causing frequent cold waves and snowfall
⑦ Equatorial Wave
○ Tip: Think of it as a westward wave flipped on the x-axis
○ The part protruding northward is called the pressure trough
○ Low-pressure develops at the eastern surface of the upper-level high-pressure trough
4. Weather Forecast
⑴ The Necessity of Weather Forecast
⑵ Formation of air masses
⑶ Transformation of air masses
⑷ Classification of air masses
① Arctic air mass (A)
② Polar continental air mass (Pc)
③ Polar maritime air mass (Pm)
④ Tropical continental air mass (Tc)
⑤ Tropical maritime air mass (Tm)
⑥ Equatorial air mass (E)
⑦ Monsoon air mass (M)
⑧ Superior air mass (S)
⑸ Air masses near Korea
① Siberian air mass
○ Origin : Siberian continent
○ Primarily observed in winter, spring, and autumn
② Sea of Okhotsk air mass
○ Source : Sea of Okhotsk
○ Visible in spring and autumn
○ Brings hot, dry winds to the western regions of South Korea in early summer
③ North Pacific Polar Front
○ Source : Southern Ocean
○ Mainly visible in summer. Also visible in spring and autumn.
④ Yangtze River Polar Front
○ Source : Chinese mainland
○ Spring and autumn
⑤ Equatorial Front
⑹ Discontinuity Line Shape
① Low Pressure Area
② Subtropical Low
③ High Pressure Area
④ V-Shaped Low Pressure Area
⑤ Anticyclonic Low Pressure Area
⑥ Siberian High
⑦ Straight Isobar
⑺ Front
① Margules’ Formula
② Warm Front : Explained with respect to the Northern Hemisphere
○ Wind direction changes clockwise as a warm front passes
○ Sequence of cloud appearance : Cirrostratus → Altostratus → Nimbostratus
③ Warm/Cold Front
④ Occluded Front
⑻ Tropical Cyclones and Typhoons
① Tropical Cyclone
○ Lowest pressure at the center of the cyclone : (Note) Same for typhoons
② Typhoon
○ Names of Typhoons : Willy-willy, Cyclone, Typhoon, Hurricane
○ Structure of a Typhoon
Figure. 9. Dangerous Semicycle and Navigable Semicycle of a Typhoon
○ Eye of the Typhoon : Weather is clear due to sinking air
○ Wind speed increases as the typhoon approaches the center, then rapidly decreases within the eye
○ Typhoon rotates counterclockwise due to Coriolis effect
○ Dangerous semicircle in the Northern Hemisphere is on the right with respect to the typhoon’s movement ( ∵ westerlies)
○ Navigable semicircle is on the left
○ Typhoons do not form along fronts
○ Typhoon Development
○ Wind direction changes clockwise as the typhoon passes
○ Generally, around latitude 30°, the direction shifts : At the equator, Coriolis effect is zero, so typhoons don’t form
○ Forms over ocean with sea surface temperature of 27 ℃ or higher
○ Typhoon accelerates after a change in direction
○ Warmer sea surface temperatures promote typhoon development
○ Typhoons often coincide with spring tides
○ Typhoon Dissipation : When a typhoon makes landfall, moisture supply is cut off, weakening the typhoon
○ Interpretation of Typhoon Observations
Figure. 10. Results of Observing a Typhoon Moving Northeastward
○ As the typhoon center approaches, pressure decreases, and wind speed increases : (a) corresponds to wind speed
Considering wind speed changes, the typhoon center doesn’t pass directly over the observation station
As the typhoon approaches, wind direction changes from northeast to southeast to southwest
Since wind direction changes clockwise, this observation station is on the right side of the typhoon’s path
③ Comparison between Tropical Cyclones and Typhoons
Table. 1. Comparison of Tropical Cyclones and Typhoons
⑼ Warm High and Cold High
① Warm High : Also known as Subtropical High or Great High
Figure. 11. Warm High
○ Warm High forms due to subsidence in the atmosphere’s circulation
○ Center of Warm High has higher temperatures than the surroundings : Warm air from the equator moved in
North Pacific High is a representative warm high
② Cold High : Also known as Subpolar High
Figure. 12. Cold High
○ Cold High forms as air cools over cold surfaces
⑿ Zenithal and Local Wind Forecast
⒀ Long-term Forecast
5. Climate
**⑴ Climate Factors and Climate Elements
① Latitude
② Altitude
③ Soil Properties
④ Topography
⑤ Distribution of Land and Sea
⑥ Ocean Currents
⑵ Climate Zones (W. Köppen Climate Classification)
① Tropical : Region with year-round monthly average temperature over 20 ℃
② Arid : Region with 4-11 months of monthly average temperature over 20 ℃
③ Temperate : Region with 4-12 months of monthly average temperature between 10-20 ℃
④ Cold : Region with 1-4 months of monthly average temperature between 10-20 ℃ and other months below 10 ℃
⑤ Polar : Region with year-round monthly average temperature below 10 ℃
⑥ Besides W. Köppen, there are A. Supan, Miller, Trewartha, and Thornthwaite climate classifications
⑶ Climate Classification
① Tropical Rainforest Climate
② Savannah Climate
③ Steppe Climate
④ Desert Climate
⑤ Monsoon Climate
⑥ Monsoon Mediterranean Climate
⑦ Warm Humid Climate
⑧ Cold Monsoon Climate
⑨ Cold Humid Climate
⑩ Tundra Climate
⑪ Permafrost Climate
⑷ Climate Change
① Brückner’s 35-Year Cycle
② Periodic Changes and Antipodal Points
③ Arctic Ice and Climate
Input : 2016.06.22 20:54