EATS 1011 Lecture 5

 

• Co₂ has less of an impact on global warming than waper vapour, but CO₂ can be controlled, water vapour isn't something humans can control
  
• The surface temperature would be exactly the same as the effective temperature if we had no atmosphere but 30% albedo
  
• T_effective =
  
• Greenhouse effect
  
  • Dilute solar radiation heats (mostly) surface
    
  • Surface heats and emits mid-IR radiation which is absorbed(mostly) by atmospheric gases and clouds
    
    • The gases such as water vapour(clouds), carbon dioxide are what cause the greenhouse effect because they absorb radiation from the sun
      
  • Atmosphere re-radiates
    
    • Up to space
      
    • Back down to earth
      
  • Surface is heated "twice" (solar + mid-IR)
    
    • Figure 212 on slide
      
  • Red skys are caused by Rayleigh scattering
    
    • 
       
      • Where lambda is the wavelength
        
  • Albedo
    
    • Refers to visible part of the light spectrum
      
    • Albedo depends on the surface the light is directed to
      
    • Fresh snow is most reflective, 75-95% light reflected
      
    • Earth is about 30% 'albedo'
      
      • Not sure how to use the word 'albedo'
        
    • 6% reflected from atmosphere
      
    • 20% reflected by clouds
      
    • 4% is reflected naturally by the earth's surface
      
    • 51% of solar energy heats the Earth's surface
      
    • Total energy budget
      
      • 
        
    • Most infrared is absorbed by the earth's atmosphere instead of being released into space
      
    • When the sun goes down at night we don't freeze because infra red energy from the atmosphere continues heating the earth while the sun is down
      
    • 70 units of solar coming in , 50 heating the surface, after all the processing we have 70 units of energy leaving in the mid infrared
      

Earth's Energy Budget

• Top of atmosphere
  
  • 70 units of solar in balanced by 70 units of Mid-IR emitted
    
• Surface
  
  • Heated twice
    
  • Solar 51 units and 96 mid-IR units
    
  • We are heated by mid-IR at night
    
• Read slides for more details on the web
  

Seasons

• What are the drivers of the seasons
  
  • In the tropics there are no seasons
    
  • Seasons are at mid latitudes
    
• orbital parameters
  
  • ellipticity of orbits
    
    • Perihelion
      
      • 147 x 10⁶ km, 4^th january
        
    • Ephelion
      
      • 153 x 10⁶ km, 4^th July
        
    • 7% change in insolation
      
  • Insolation:
    
    • The suns energy averaged over 24 hours
      
  • Obliquity: tilt
    
    • Rotation axis – pole star
      
    • 23.5 degrees
      
    • Solstice
      
      • N pole sun 21^st June, sun overhead at noon at tropic of Cancer(23.5N)
        
      • S pole sun 21^st December, sun overhead at noon at the tropic of Capricorn (23.5S)
        
      • Regions of perpetual day and night
        
    • Equinox
      
      • Axis 90 to sun – earth line
        
      • Vernal 21^st march
        
      • Autumnal 21^st September
        
      • Effects the length of the day
        
• So what causes the seasons
  
  • Ellipticity
    
    • 7% so little impact
      
      • Except over eons
        
  • Obliquity
    
    • Large effect at mid- and polar latitudes
      
  • Latitude
    
    • In the tropics changes driven by overhead sun
      
    • Wet and dry seasons
      
    • Twice a year
      
• Length of day light for various latitudes
  
  • 
    

 

CSE 2011 Lecture 5

 

Testing and Debugging

• Create a test plan application that will probe the program with input and compare its output to see if the program is outputting the desired output from the test
  
• Verification
  
  • Does the software meet its specifications
    
• Validation
  
  • Does the software meet its requirements
    
• Identify test criteria
  
  • What are the goats for comparing the system against its spec
    
    • Reliability, completeness, robustness
      
  • Identify target components for testing
    
    • In an OO system the classes and class hierarchies
      
  • Generate test cases
    
    • Produce test cases that can identify faults in an implementation
      
  • Execute test cases against target components
    
  • Evaluation
    
    • If expected outputs are not produced, a bug report is issued
      
• Black box testing
  
  • Testing based on input and output alone
    
    • Do not consider underlying implementation
      
  • Test cases are generated from the spec
    
    • Pre and post conditions
      
  • Specific kinds of black box testing
    
    • Random testing
      
      • Generate random inputs
        
      • Easy to generate cases
        
      • Good at detecting failures
        
      • Must be able to easily generate expected output
        
    • Partition testing
      
      • Cannot try all possibly inputs
        
        • Partition input into equivalence classes
          
        • Every value in a class should behave similarly
          
      • Test cases
        
        • Just before the boundary
          
        • Just after the boundary
          
        • On a boundary
          
        • One from the middle of an equivalence class
          
      • Loops
        
        • Zero times through the body
          
        • Once through the body many times through the body
          

CSE 2031 Lecture 3

• Integer types:
  
  • char
    
  • short
    
  • int
    
  • long
    
• Floating point types:
  
  • float
    
  • double
    
  • long double
    

Char

• 1 byte long
  
• char<= short<=int<=long
  
• denote characters in single quotes
  
• \0 is a null character
  
• char *b = "TEST";
  
  • is a string writer (assumption)
    
• EOF
  
  • Reads as -1
    
    • Which is an array of ones
      
• getchar() reads a byte of unsigned chars and stores 4 bytes to represent them
  
  • the promotion to int is done as a signed char
    
  • This is because of things like EOF
    
• A signed char
  
  • Fills the other bytes with the first bit of the signed char
    
  • If it is signed and starts with 0
    
    • It is non negative
      
  • If it starts with 1
    
    • It is a negative number
      
• An unsigned
  
  • Does not fill the other 3 bytes with the first bit but with all 0's when promoted to an int
    

Declarations

• when you declare a variable in C it is visible throughout the score of the brackets that it is withheld
  
• if you want a variable to be visible throughout a program put it above the main
  
• to make one variable local to a file use the word 'static'
  

String

• an array of char
  
• there is no 'String' in C
  

Arrays

• to declare an array in C
  
  • use type name[size]
    
    • example: int number[10]
      
• you can initialize an array w/o a specified size
  
  • char s[] = {'h','e','l','l','o','\0', 'q'}
    
  • printf("%s /n", s}
    
    • returns 'hello'
      
      • note there is no q, that is because null character was before it
        

printF

• %d prints integers
  
• %s prints char characters
  
  • Prints until it finds a null character
    
  • Null character is \0
    
• %p prints the address
  

Console

• Od –cb filename
  
  • Describes a file in bits
    

CSE 2011 Lecture 4

Inheritance

• An object is a collection of data and methods to operate on that data
  
  • Method is a procedure, function, operation
    
• For a motor
  
  • turnOn
    
  • turnOff
    
  • setSpeed
    
• An Object is an instance of a Class
  
  • The class provides the template for the object
    
• Template gives
  
  • Data
    
  • Methods
    
• Class contains methods, objects contain the data
  
  • Typically pictured as an object pointing to the class
    
  • Because the object uses methods
    
  • Objects share methods
    

Container

• A collection of data is stored in a container
  
  • The data can be of different sub-types
    
• Containers can be organized in different ways
  
  • Sequence,
    
  • Tree's
    
  • Table
    

Sequence

• A list of objects in order
  
  • Contains a head, front, tail and last
    
  • Sequence = <head. ^ tail = front ^ <last>
    

EATS 1011 Lecture 4

• In the northern hemisphere high pressure system goes clockwise, low pressure systems go counter-clockwise
  
  • This is due to the 'Coriolis effect'
    
• GEOS bright colours represent 'cold'
  

  
  

  
  

• E_Å
  is the solar energy at 1 AU ("constant")
  
• 1 AU = 1.5.10⁸ km = 1.5.10¹¹ m
  
• E_Å
  = L_ʘ/( 4.pR_p²) = L_ʘ/( 4.p1 AU)²)
  
• = 1.38.10³ W m^-2
  
• L_ʘ
  = E_Å
  4.p(1 AU)²
  
• E(Rp) = L_ʘ/( 4.pRp²) = E_Å
  /(Rp/1 AU)²
  
• = E_Å
  /Rp²
  
• Rp measured in AU
  

• 37% of energy from the solar spectrum is near infrared
  

  
  

• Most energy from the sun is less than 1 micron
  

  
  

• We can see light where the sun outputs the most energy
  

  
  

• The sun emits mostly in the UC, visible and near infrared regions
  

  
  

• Humans can only see the visible region
  

  
  

• The earth emits almost all in the mid infra red region
  

  
  

• Satellites measuring IR can pick up differences in temperatures (clouds, water, surface, etc)
  

  
  

• The area under the solar-radiation curve is the total (all wavelengths) solar radiance reaching the earth's orbit
  

  
  

  • =1.38*10³ W m^-2
    

Planetary Effective temperatures

• The sun is far enough away to consider its rays parallel to eachother
  
• Some light scatters back into space
  
• The difference between infra red and solar energy is solar energy only comes through during the day
  
  • Emitted light as opposed to scattered
    
• Albedo
  
  • A =
    
• Radius of planet, b
  
• Atmosphere emits as Planck body, sT⁴ W/m²
  
• Steady state energy balance
  
  • Heating = cooling
    
• Absorption (area*flux) = emission(area*flux)
  
  • 
    

• Total amount of energy intercepted = π b²
  
• T_eff = effective temperature
  
• Earth, rp 1AU
  
• Albedo = .3 ( i.e. 70% of energy absorbed)
  
  • T_eff = 255 Kelvin, = -18 Celcius
    
• But The mean temperature is about 15 Celcius
  
  • T = 33 celcius
    
• What is the implication for this temperature difference?
  
  • Natural greenhouse effect
    
    • Main greenhouse gas in the atmosphere is water vapour
      
• Earth radiates / cools in the mid – IR (Wien's Law) from about 5km
  
• Obliquity
  
  • the tilt of the planet from the sun
    
  • 
    
• Mercury – rotates slowly and has a very large d/n temperature difference because heat deposited locally cannot be rapidly transferred to other locations such as the night side
  
• Venus – T of 700k is actually the surface temperature and is evidence of a large greenhouse effect
  
• Earth - natural greenhouse effect of about 33C
• Mars - small greenhouse effect
• Jupiter - interior heating - gravitational contraction
• saturn - same
• uranus - no
• neptune - same as J and S
• Pluto - aerosols and methane lead to a greenhouse effect
  

Heating of the Earth by Radiation

• Solar radiation incident on atmosphere
  
  • Dilute 6000 K radiation
    
  • Scatters off air, clouds (numbers later)
    
  • Absorbed by aerosols, clouds, gases
    
  • Overall visible fairly transparent
    
  • Surface absorbs most radiation
    
    • Albedo trees(15%, ocean 10%)
      
  • Mid-IR radiation emitted from Earth / atmosphere system
    
  • Also called terrestrial radiation / long wavelength
    
  • Mid-IR is quite absorptive
    
  • "windows" 8-9, 10-12 чm
    
  • Main absorbers
    
    • H₂O, CO₂, clouds
      
  • Seconday absorbers
    
    • CH₄, N₂O, CFCI₃,CF₂Cl_2, O₃
      
  • Absorption of radiation
    
    • For graph on absorption
      
      • 100 = total absorption
        
      • 0 = no absorption
        
    • O₂ and O₃ absorb very energetic radiation from the sun
      
    • At about 9.6 microns ozone is acting as a greenhouse gas
      
  • Nitrous oxide
    
    • No role in visible spectrum
      
    • At about 4 microns and 6 microns absorbs quite a lot of energy
      
  • Methane
    
    • Heats the atmosphere a little bit
      
    • Plays a major role at about 6 microns
      
  • Water vapour
    
    • Water vapour absorbs a long range
      
      • Short mid and long range
        
      • From 4 -8 microns it plays a major rold
        
      • Plays a major role in controlling earths temperature
        
  • Carbon dioxide
    
    • Heats the atmosphere because it absorbs infrared radiation
      
    • Major band at about 15 microns
      
• Most visible radiation goes to the surface
  

Transmission of solar and IR radiation

• 
  

CSE 2031 Lecture 2

Course Information

15% on assignments

30 % on midterm

Rest on exam

 

Recap from day 1

• -Wall
  
  • Shows any errors the compiler wouldn't typically catch
    
• -o
  
  • Allows you to change the executable files filename
    
• -c
  
  • Stops compilation after the object module is produced
    
• -E
  
  • Stops the compilation after the preprocessor phase
    
  • Textual manipulation of the source code
    

 

#include <stdio.h>

int main(void)

{

    int n, m;

    int product = 1; /* will eventually hold n!*/

    scanf("%d, &n);

    m=n;

    while ( m > 0)

        product *= m--;

    printf("%d! = %d\n", n, product);

    return 0;

}

 

#include <stdio.h>

 

int factorial(int) /* must be declared here in case user inputs a non-int*/

int main(void)

{

int n;

scanf("%d", &n)

printf("%d! = %d\n", n, factorial(n));

return 0;

int factorial(int x)

{

    /* base case*/

if (x<2) return 1;

    /*recursive calls*/

return x*factorial(x-1);

}

/*returns 5! = 120*/

}

If you want to compile with two files linking eachother use

• cc -0 printFactorial factorial.c printfactorial2.c
  
• this will link the code used in printFactorial from factorial.c so that printFactorial will work
  
  • this is more explicit than java because there isn't an 'import' feature
    
  • instead the feature is found in the compiler
    
• when you compile a program that uses multiple files you have to name all the files on the command line
  
• utility 'make'
  
  • merges files together
    
  • looks for a 'makefile'
    
    • in a make file there are dependency lines or action lines
      
      • action lines MUST be tabbed over
        
    • dependency lines describe the files in use
      
    • action lines tell console what to do to generate the file described in the dependency file
      
  • when 'make' is typed in console it runs the commands found in makefile
    
  • read makefile on course website, when it is available
    
    • console: make clean
      
    • runs the clean command found in 'makefile'
      
    • all warning flags are put in 'makefile' such as –Wall
      
• Compiler
  
  • –l makes the console look in the library for functions used that aren't in stdio.h
    
  • –lm looks in the m (math) library
    

 

#include <stdio.h>

#include <math.h>

int main(void)

{

    double x;

    

    printf("Enter value for x: ");

    scanf("%1f", &x);

    

    printf("x = %f sqrt(x) = %1f\n", x, sqrt(x));

    return 0;

}

s

Array as an Abstract Data Type

• What is an array?
  
  • An indexed, homogeneous collection of variables
    
  • Indexed from n-1 where n is the size
    
  • Multi dimensional
    
    • 1 index per dimension
      
  • The upper bound must be greater than or equal to the lower bound
    
• An integer
  
  • is four bytes long, in sequence
    
• to put one thing in to memory is called 'mapping'
  
• row order is where the rows are separated and the columns are adjacent
  
  • column order is the opposite
    
• if you have an array going from [-5 ..+6, +1 … 10, 3…5] of chess pieces
  
  • you would have an array of
    
    • -5, …, +6 of
      
      • An array of 1 , … , 10 of
        
        • An array of 3, …, 5 of chess pieces
          
• Index – lower bound , to find the memory location of an object in a one dimensional array
  
  • For multi dimensional the 2^nd 3^rd… n dimensions start at the end point of the first but find an index the same way as a 1 dimensional array
    
• Array Descriptor
  
  • Dimension count
    
    • For each dimension it needs to lower bound and upper bound and total size
      
    • A prototype array descriptor
      
      •     
        
• A₀ is the hypothetical location in memory where the first lower bound is found in memory.