global climate change-major content - ranjanranjan.net.np/lectures/crisis/lect3.pdf · 6/6/2017 3...
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Natural Climate Change (Including Paleoclimate- Changes in Climate)The Hydrologic Cycle
Associate Professor, Geodisaster Research Center, Central Department of Geology, Tribhuvan University, Kirtipur, Kathmandu, Nepal
Visiting ProfessorFaculty of Engineering, Kagawa University, JAPAN
Visiting Associate ProfessorCenter for Disaster Management Informatics Research, Ehime University, JAPAN
Fellow AcademicianNepal Academy of Science and Technology (NAST)
Ranjan Kumar Dahal, PhD, PostDoc, M.ASCE
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Global Climate Change- major content10 hours
Introduction to the Climate System
Global Energy Balance, Radiate - (Light & Heat) Transfer and Climate
Energy Balance at the Surface
Natural Climate Change (Including Paleoclimate-Changes in Climate)
The Hydrologic Cycle
Climate Sensitivity and Feedback Mechanisms
Anthropogenic Climate Change
International Climate Change Bilateral and Multilateral Negotiations
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Before we begin: – review of last class1. “Sky is blue” justify this statement.
2. We have four seasons. Why?
3. Differentiate “Leaky Green House effect” and “Normal Green House effect”
4. Write surface energy balance equation.
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Basic Concepts: energy budget of the earth-atmosphere system
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Overview – Climate Change Introduction to Climate Change
Causes of Global Climate Change
Effects of Climate ChangeMelting Ice and Rising Sea
Level Changes in Precipitation
Patterns Effects on Organisms Effects on Human Health Effects on Agriculture
Dealing with Global Climate Change
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What is Climate Change? Climate is the average weather at a given point and
time of year, over a long period (typically 30 years).
We expect the weather to change a lot from day to day, but we expect the climate to remain relatively constant.
If the climate doesn’t remain constant, we call it climate change.
The key question is what is a significant change –and this depends upon the underlying level of climate variability
Crucial to understand difference between climate change and climate variability…
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Climate Change Evidence for Climate Change
11 of the 12 years between 1995 and 2006 were among the twelve warmest years since the mid-1800s
Phenological spring in N. hemisphere now comes 6 days earlier
Warming is not due to natural causes
Human produced greenhouse gases are most plausible explanation
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Key Sources of Information
The Intergovernmental Panel on Climate Change (IPCC) (www.ipcc.ch)
Authoritative reports supported by >95% of climate scientists
Fourth assessment report (AR4) published 2007
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Causes Greenhouse gas concentrations increasing
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Earth’s carbon cycle
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Methane and other greenhouse gases
Generally present at lower concentrations than CO2.
More complicated molecules with more polar bonds have more and stronger IR absorption bands –global warming potential (GWP).
Relative importance is given by the product of concentration and GWP.
Atmospheric lifetime is important – of the long-lived greenhouse gases (LLGHGs), methane has the shortest lifetime, being susceptible to reaction with OH.
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Methane 40% from natural sources
Decaying vegetation, marsh gas.
Agriculture, especially rice paddies with anaerobic bacteria.
Ruminants (cattle and sheep)
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Nitrous oxide (NO2) “laughing gas”
Bacterial conversion of nitrate (NO-3) from
soils
Catalytic converters
Ammonia fertilizers
Biomass burning
Nylon and nitric acid manufacture
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The Greenhouse Effect and Atmospheric Warming
• Greenhouse effect: greenhouse gases (CO2, H2O, N2O, O3, CH4, CFCs) absorb energy of longwave radiation and re-radiate some energy back to the earth’s surface to keep it warm
• Without greenhouse gases, the earth’s surface air temperature would be much colder
• If the amount of greenhouse gases increase, the surface air temperature will increase (global warming)
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CH4: natural gas production, landfills, agriculture, global warmingN2O: NO3
- (bacteria), automobiles, industrial processes
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Increased concentration of CO2
(right)
Burning fossil fuels in cars, industry and homes
Deforestation
Burning of forests
Causes
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Greenhouse Effect
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Other Pollutants Cool the Atmosphere
Atmospheric Aerosols tend to cool the atmosphere
Both human and natural sources
Tiny particles that remain in troposphere for weeks or months
Contain many chemicals, but often contain sulfur
Complicates models of climate change
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Climate Change-Mean Annual Global Temperature 1960-2005
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Climate Change Terminology Greenhouse Gas
Gas that absorbs infrared radiation Ex: Carbon dioxide, methane, nitrous oxide,
chlorofluorocarbons and tropospheric ozone Positive Feedback
Change in some condition triggers a response that intensifies the changed condition
Infrared Radiation Radiation that has a wavelength that is longer than
that of visible light, but shorter than that of radio waves
Greenhouse Effect Increase of heat in a system where energy enters
(often as light), is absorbed as heat, and released sometime later
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100 0.0740.018
50 0.1280.026
Warmest 12 years:1998,2005,2003,2002,2004,2006, 2001,1997,1995,1999,1990,2000
Period Rate
Years /decade
Global mean temperatures are rising faster with time
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Global surface temperature 1855-2010
How is this curve calculated?
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Observed surface temperature trend
Trends significant at the 5% level indicated with a ‘+’. Grey: insufficient data
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Other evidence of Climate Change
Glacier retreat
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Melting Ice and Rising Sea Levels
1957
1998
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Glaciers and frozen ground are receding
Area of seasonally frozen ground in NH has decreasedby 7% from 1901 to 2002Increased Glacier retreat since the
early 1990s
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Snow cover and Arctic sea ice are decreasing
Spring snow covershows 5% stepwise drop during 1980s
Arctic sea ice area decreased by 2.7% per decade(Summer: -7.4%/decade)
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Other evidence of Climate Change Ocean heat content has increased
Temperatures in the Atlantic:
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Change in heat content over last 50 years
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Rise in global ocean heat content 1955-2005
Some ups and downs, but clear overall increase
Levitus et al., 2005, GRL
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Sea-level from satellites: 4 cm rise
in last 10 years
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Evidence from Phenology (timings of natural events)
www.phenology.org.uk
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Some aspects of climate have not been observed to change:
Tornadoes
Dust-storms
Hail
Lightning
Antarctic sea ice
Direct Observations of Recent Climate Change
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Warming in last 100 years appears exceptional. But is the uncertainty range (the spread of different reconstructions) large enough?
Northern Hemisphere Temperature AD 700-2000 –several different reconstructions from proxy data
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Ice cores – store past samples of the atmosphere
Bubbles of airtrapped whenice formed
Analyse oxygen isotopes => Temperature
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Effects of Global Climate Change Ocean as CO2 sink - excess CO2 is starting to harm
ocean life
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Effects of Global Climate Change-Melting Ice and Rising Sea Levels Sea level rise caused in 2 ways
Thermal Expansion Water expands as it warms
Melting of land ice Retreat of glacier and thinning of ice at the
poles
Melting has positive feedback
Increased melting decreases ice, which decreases albedo leading to further warming
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Case-In-Point Impacts in Fragile Areas
Eskimo Inuit live traditional life dictated by freezing climate
Climate change is altering their existence Wildlife are smaller or
displaced
Reduced snow cover and shorter river ice seasons
Thawing of permafrost (right)
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Some areas will get more water, some areas will have greater droughtsEx: Hurricanes will likely get stronger
Effects of Global Climate Change-Changing Precipitation Patterns
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Zooplankton in parts of California Current have decreased by 80% since 1951
Effecting entire food chain
Decline in krill around Antarctica
Caused decrease in penguin populations
Species have shifted their geographic range
Migrating birds are returning to summer homes earlier
Food is not available at this time
Effects of Global Climate Change- Effects on Organisms
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Effects on Organisms - Coral Reefs
Coral reefs can be bleached (right) due to increase in water temperature
Affects coral symbiotes and makes them more susceptible to diseases to which they would otherwise be immune
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Effect on Organisms - VegetationBeech Tree Range
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Effects on Human Health
Increased number of heat-related illnesses and deaths
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Effects on Agriculture
Difficult to anticipate Productivity will increase in some areas and decrease
in others
Rise in sea level will inundate flood plains and river valleys (lush farmland)
Effect on pests is unknown
Warmer temperatures will decrease soil moisture- requiring more irrigation
Location (i.e. elevation and altitude) where certain crops can be grown may have to change
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Climate Models Climate affected by:
winds, clouds, ocean currents, and albedo
Used to explore past climate events
Advanced models can project future warming events
Models are only as good as the data and law used to program them They have limitations
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Climate Models
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International Implicationsof Climate Change
Developed vs. Developing countries
Differing self-interests
Differing ability to meet the challenges of climate change
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Dealing with Global Climate Change
To avoid the worst of climate change, CO2levels must be stabilized at 550ppm50% higher than current levels
Two ways to attempt to manage climate changeMitigation
Focuses on limiting greenhouse gas emissions to moderate global climate change
Adaptation Focuses on learning to live with to the
environmental changes and societal consequences brought about by global climate change
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Dealing with Global Climate Change- Relationship Between Mitigation and Adaptation
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Dealing with Global Climate Change- Mitigation
Locate/invent alternative fuels to fossil fuels
Increase efficiency of cars and trucks
Sequestering carbon before it is emitted
Plant and Maintain trees to naturally sequester carbon
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Dealing with Global Climate Change-Adaptation Rising sea levels
and coastal populations
Move inland Construct
dikes and levees
Adapt to shifting agricultural zones
NYC sewer line
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Rate ofchangeofcombinedforcing
Grey bars:natural variabilitylast 650,000 yrs
IPCC(2007)
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Reduction of Carbon Emissions
Burn less fossil fuel: Turn down your thermostat
Plant Trees for shade and CO2 uptake
Insulate your house
Replace old appliances
Use compact fluorescence/led light bulbs
Use renewable energy
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Climate change summary Global surface temperatures have risen by about
0.6°C since 1900 It is likely that this warming is larger than for any
century since 200AD, and that the 1990s were the warmest decade in the last millennium.
The warming differs in different parts of the world, but over the last 25 years, almost everywhere has warmed, and very few places have cooled.
Other changes have occurred, e.g.: Sea level has risen by about 20 cm, Ocean heat content has increased, Almost all mountain glaciers have retreated
Coincident with this global warming, levels of CO2(and other ‘greenhouse’ gases) have dramatically increased, to levels higher than those experienced for maybe millions of years.
Year Annual Monsoon
1963 1477.1
1964 1484.7 1423.9
1965 1131.6 1063.5
1966 1386.6 1312.2
1967 1068 962.6
1968 1131.8 1021.3
1969 2190.5 2045.2
1970 1601.7 1466.3
1971 2299.5 1855.1
1972 1701.7 1565.1
1973 1935.6 1329.9
1974 1220.8 1120.7
1975 2100.7 1933.5
1976 1182 1076.6
1977 1303.2 989.4
1978 2111.6 1886.7
1979 1106 703.2
1980 2122 1783.9
1981 2233.9 1790.4
1982 1696.8 1264.5
1983 1709.2 1083.2
1984 1418.5 1129.6
1985 2355.1 1879.2
1986 1585.4 1203.7
1987 1108.3 844.6
1988 1939.6 1549.8
1989 849.3 634.1
1990 2038.6 1683.6
1991 969.8 774.1
1992 715.7 572.4
1993 1039.8 929.5
1994 875.6 769.3
1995 676.4 509.4
1996 1088.4 819.5
1997 1242.5 802.7
1999
2000 1109.3 963
2001 1012.1 894.8
2002 899.5 662.1
2003 737.3 613.3
2004 520.5 471.5
2005 573.6 436.6
2006 940.9 773.8
2007 759 661.3
2008 87.2 43
2009 1067.1 759.6
2010 1256.7 1057.2
2011 1004.1 869.9
2012 1036.3 914.7
2013 1798.9 1451.5
The tables show Rainfall data from Surkhet station.Plot year vs rainfall graphs for annual and monsoon rainfalls and identify the trend line of both rainfall patterns
Class work
Time 30 min
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0
500
1000
1500
2000
2500
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 2015
Year
Ave
rage
Monsoon Rainfall (m
m)
Annual
Monsoon
Linear (Annual)
Linear (Monsoon)
An
nu
al a
nd
mo
nso
on
rai
nfa
ll
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Hydrological Cycle
• All streams flow into the sea, yet the sea is never full.
To the place the streams come from, there they return again.
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Hydrologic CycleChange in Annual Precipitation
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Hydrologic CycleModeled Environmental Water Scarcity Index• Scarcity is where the amount of water removed from the system puts the • ecosystem at risk by tapping into the environmental water demand, i.e., the amount of water needed to sustain the integrity of the ecosystem• Areas above 0.4 are under ecosystem environmental stress• Areas higher than 0.8 (orange and red) are highly-stressed environmentally
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The Water Cycle
425 Evaporation
71 Evapotranspiration
111 Precipitation
385 Precipitation
40 Vapor Transport
Surface Runoff
Groundwater Flow
Percolation40
Return Flow
1012 m3 per year
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Mean Global Precipitable Water (cm)• Annual Average
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S.W. Seemann, J. Li, W.P. Menzel – Univ. Wisconsin, NOAA
Mean Global PrecipitableWater (cm)
• Seasonal variability
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Clouds and PrecipitationAtmospheric Saturation Processes
• Add moisture - Infrequent (Steam Fog)
• Cool to dew point temperature - Usual process
- Lifting
- Mixing
- Radiation
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Clouds and PrecipitationCloud Formation
• Condensation process
- Condensation nuclei
> What are they?
‡ Sea salt‡ Combustion products - smoke‡ Dust - Clay from plowed fields
> What is their distribution?
• Decrease with height • More over cities than country• More over land than ocean - More giant nuclei over oceans
- Hygroscopic nuclei - Begin to attract water vapor at humidity as low as 70%
> What are they?
‡ Sea salt - Most common
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Types of Condensate
• Dew
- Caused by radiational cooling of a surface to the dewpoint temperature of the air
- Typical conditions
> Clear sky> Calm winds (little mixing)> Night time
- Dewpoint temperature above 0oC
Clouds and Precipitation
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Clouds and PrecipitationTypes of Condensate
• Frost
- Caused by radiational cooling of a surface to the dewpoint temperature of
the air
- Typical conditions
> Clear Sky> Calm winds (little mixing)> Nighttime
- Dewpoint temperature below 0°C
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Clouds and PrecipitationTypes of Condensate• Fog
- Defined as a cloud on the ground
- Caused by
> Cooling of the air to its dewpoint temperature
‡ Most common cause‡ Types of “cooling fog”
◊ Radiation fog◊ Advection fog◊ Upslope fog
> Evaporation of enough water to saturate the atmosphere
‡ Least frequent cause‡ Types of “evaporation fog”
◊ Steam fog◊ Warm-rain fog
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Clouds and Precipitation
Types of Condensate
• Haze
Caused by particles (“large”) that scatter all wavelengths of light equally
Increases as humidity becomes greater than 70% because of hygroscopic nuclei
• Cloud dropletsCooling of the air aloft to its dewpoint temperature
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Clouds and PrecipitationAtmospheric Particles
Name Diameter (cm) # per cm3
Large Ions 10-6 to 10-5 103 to 104
Smoke and Dust 10-5 to 10-4 variable
Large Condensation Nuclei 10-5 to 10-4 102
Giant Condensation Nuclei 10-4 to 10-2 1
Cloud Droplets 10-4 to 10-2
Rain Drops 10-2 to 1
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Clouds and Precipitation
Particle Terminal Velocities
Particle Type Diameter (cm) m/s mphCondensation Nuclei 2 X 10-5 1 X 10-7 2 X 10-7
Small Cloud Droplets 1 X 10-5 3 X 10-3
Typical Cloud Droplets 2 X 10-3 1 X 10-2 2 X 10-2
Large Cloud Droplets 10-2 0.27 0.18
Small Rain Drops 0.1 4.0 8.9
Typical Rain Drops 0.2 6.5 14.6
Large Rain Drops 0.5 9.0 20.1
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Clouds and PrecipitationRaindrop Growth Process
• Raindrop 100 times larger diameter than cloud drop; 1,000,000 time larger volume
• How does this tremendous growth occur?
- Coalescence process - “Warm” clouds
> Terminal velocity
‡ Gravitational force‡ Pressure gradient force‡ Drag force
> Large drops fall faster than smaller drops> Large drops collect smaller drops
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Cumulonimbus
AltostratusNimbostratus
Cumulus
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Clouds and PrecipitationPrecipitation Classification
• Drizzle- Small, numerous drops falling out of fog or low layer stratus clouds- Indicative of stable stratification with little vertical motion
• Intermittent or Continuous Precipitation- Rain or snow- Falling more or less evenly from altostratus or nimbostratus clouds- Caused by widespread and slow upward movement of large masses
of air
• Showers (Squalls, Flurries)- Precipitation with short duration with fair intervals- Caused by cumulus or cumulonimbus clouds, i.e, convection- Indicative of unstable stratification with fairly strong upward vertical
motion in localized regions
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Clouds and Precipitation
Types of Precipitation
• Virgae- Rain that evaporates below cloud base, but before reaching the ground
• Rain- Lower atmosphere above freezing- Drops large enough to fall relative to
air motions
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Clouds and PrecipitationTypes of Precipitation
• Freezing Rain
- Ground at 0°C or colder- Very shallow layer of air near the ground
at near 0°C or colder- Layer of air above this shallow layer at
temperatures above 0°C
http://www.srh.noaa.gov/lzk/html/win121300.htm
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Clouds and Precipitation
Types of Precipitation
• Sleet, Grauple, Ice Pellets
- Clear ice “drops”- Precipitation is in the form of liquid drops at
sometime as it falls- Deeper layer of air above the ground
at 0°C or colder- Layer of air above this deeper layer at
temperatures above 0°C
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Clouds and PrecipitationTypes of Precipitation
• Snow- Opaque ice crystals or flakes- Crystals form at temperatures below 0°C
by the process of deposition- No liquid phase- Ground at or near 0°C or colder- Layer of air above the ground at
temperatures below 0°C
http://www.ucar.edu/imagelibrary/1100-1133.html
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Clouds and PrecipitationTypes of Precipitation
• Hail- Large balls or lumps of ice- Often formed of concentric
rings of clear and opaque ice
- Formed in clouds with strong updrafts, i.e., convective clouds
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THE WATER CYCLE
EVAPORATION
CONDENSATION
PRECIPITATION
SURFACE RUNOFF
INFILTRATION
TRANSPIRATION
A. Rain, Snow, Sleet, Hail
B. Water vapor turning to liquid
C. Water flowing on the surface of the land
D. Plants are needed
E. Water absorbing into the soil
E. Liquid changing states to a gas
Draw lines to connect the parts of the water cycle to a description of the part
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7th Lecture
Next class
Climate Sensitivity and Feedback Mechanisms
Anthropogenic Climate Change
Home work:1. Enter the data of annual rainfall and annual
monsoon rainfall in excel sheet and plot graphs with trend lines as prepared in the class work
2. The data is from Surkhet station western Nepal, what is your opinion on climate change scenario in the Surkhet region of western Nepal.
Submission Date: 2017/06/13, till 10 am.Lecture note:
http://www.ranjan.net.np/lectures/crisis/lect3.pdf