Agricultural Science Climatology Semester 2, 2006 Anne Green / Richard Thompson http://www.physics.usyd.edu.au/ag/agschome.htm Course Coordinator: Mike Wheatland
Course Goals Evaluate & interpret information, based on scientific arguments Understand the physical principles relevant to your field of study Use scientific terminology correctly Be able to appreciate the analysis essential to developing a model of the physical environment
Preparation for Workshops Students should read Workshop Notes before Class Marks are awarded for Group Contribution at the end of the Workshop: 0 to 5 marks Teams of 6 students for Workshops & Lab Classes - must know team number e.g. 1A 1B, 13A 13B, 23A 23B Workshops held in Second Year Laboratory in School of Physics - sit at a space where there is an A3 sheet marked with team number for the team mind map.
Mind Maps Visual summary of content of Workshop Notes List scientific terms (include units for physical quantities) on far left of A3 sheet List physical principles, laws, definitions, equations, maths, graphs, etc on the left of the A3 sheet Use colour, pictures, or diagrams to emphasize key ideas and concepts Collect relating information into "boxes Indicate how ideas are linked together Summarize notes with minimum words (no padding words "e.g.", "a", "the", "when", etc)
Example of a Mind Map
Web Based Activities Activities 1 & 2 at the due date of Activity 2 which is 19 September Activities 3 & 4 should both be handed in on 10 October Activity 5 does not need to be handed in (it is to be done in week 13 Remember that material from the web activities may be included in the examination
SI System of Units distance - metres m time - seconds s speed - m.s -1 energy - joules J power - watts W intensity - W.m -2 mass kg temperature - kelvin K Other units: Energy - kilowatt hours kw.h (1 kw.h = 3.6x10 6 J) Time - hours h Power - kilowatts kw (1000 W = 1 kw) Prefixes: nano micro milli kilo k mega giga G n µ m M 10-9 10-6 10-3 10 3 10 6 10 9
Chapter 1 Weather, Climate and Agriculture Weather and climate are fundamental to agriculture. Both are driven by radiation from the sun and depend on a variety of astronomy (such as the seasons) and physics. It is important to have an understanding of these processes.
Earth and Sun
Weather & Climate Climate long-term patterns in the air surrounding us. Weather daily variations in temperature, rainfall, air pressure, humidity, wind. Climates change on different time-scales. Principle drivers of weather water in the atmosphere and radiation from the sun.
Climate for Alice Springs in July Mean daily maximum temperature - deg C 19.6 Mean no. of days where Max Temp >= 40.0 deg C 0 Mean no. of days where Max Temp >= 35.0 deg C 0 Mean no. of days where Max Temp >= 30.0 deg C 0 Highest daily Max Temp - deg C 31.6 Mean daily minimum temperature - deg C 4 Mean no. of days where Min Temp <= 2.0 deg C 12.5 Mean no. of days where Min Temp <= 0.0 deg C 6 Lowest daily Min Temp - deg C -7.5 Mean monthly rainfall - mm 14 Median (5th decile) monthly rainfall - mm 2.6 9th decile of monthly rainfall - mm 37.4 1st decile of monthly rainfall - mm 0 Mean no. of raindays 2.6 Highest monthly rainfall - mm 144 Lowest monthly rainfall - mm 0 Highest recorded daily rainfall - mm 76.8 Mean no. of clear days 21.4 Mean no. of cloudy days 4.2 Mean daily hours of sunshine 9.1 Highest recorded wind gust - km/h 90.7 Mean daily evaporation - mm 3.9
Weather Map for July 13, 2006
Our Climate Does Vary (1) Areas with above average rainfall 1950 1951 100 Sea surface temp: % warmer than normal 90 80 70 60 % 50 40 30 20 10 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Our Climate Does Vary (2) Snow depth for the NSW Alpine areas. The year 1981 was a record good year but 1982 was the worst on record!
Our Climate Does Vary (3)
Our Climate Does Vary (4) Deceived by several years of excellent rainfalls and believing that 'rain would follow the plough', farmers went beyond the safe agricultural areas. When agricultural land became scarce in the settled districts, combined with the good seasons and crops during the early 1870s, the government decided to disregard Goyder's Line and allow farmers to buy land north of it.
Our Climate Does Vary (5) For several years it looked as if Goyder had been wrong as rain just kept on falling every year. During the winter of 1882 it looked as if 'the rain did indeed follow the plough. By the end of 1883 farmers could not believe their eyes. The good feed had gone, and Blinman, which had a year before been called 'one of the healthiest places in South Australia' was now nothing more than a dustbowl.
European Temperature (longer timescale) 1.6 Temperature fluctuation / C 1.4 1.2 1.0 0.8 0.6 0.4 0.2 Little ice age 0.0 900 1100 1300 1500 1700 1900 year
Source: NASA Global Temperature (1880-2004)
Earth s Place in the Solar System Sun source of radiation and solar wind. Seasons due to tilted Earth revolving about the Sun, not variation in distance. Variation in light & warming over the year. How does the Sun move during the year? (page 30) Electromagnetic spectrum not uniform transmission through the atmosphere. (page 163)
The Sun in Ultraviolet Light
Layers of the Sun
Solar System from Space Source: NASA Simulator
The Planets of the Solar System Source: NASA (not pictured Pluto)
The Seasons (1)
The Earth at Different Seasons Wikipedia
Source: Wikipedia The Seasons (2)
Source: Wikipedia The Seasons (3)
Daylight Region (Northern Summer Solstice)
Daylight Region (Equinox)
Daylight Region (Southern Summer Solstice)
Co-ordinate System for Stars
Solar Declination through the Year
Zenith Distance / Altitude of Sun Sydney at Noon Winter Solstice (35 + 23.5 = 58.5 deg / 31.5 deg) Equinox (35 + 0 = 35 deg / 55 deg) Summer Solstice (35 23.5 = 11.5 deg / 78.5 deg)
Dates for the Astronomical Seasons UTC Date and Time of Solstice and Equinox year Equinox Mar Solstice June Equinox Sept Solstice Dec day time day time day time day time 2004 20 06:49 21 00:57 22 16:30 21 12:42 2005 20 12:33 21 06:46 22 22:23 21 18:35 2006 20 18:26 21 12:26 23 04:03 22 00:22 2007 21 00:07 21 18:06 23 09:51 22 06:08 2008 20 05:48 20 23:59 22 15:44 21 12:04 2009 20 11:44 21 05:45 22 21:18 21 17:47 2010 20 17:32 21 11:28 23 03:09 21 23:38
Seasons in Australia Start Middle End Summer December 01 mid January February 28/29 Autumn March 01 mid April May 31 Winter June 01 mid July August 31 Spring September 01 mid October November 30
Temperature Lag 30 Temperature Variations for Sydney Summer Solstice Mean Maximum Temperature 25 20 15 10 5 Winter Solstice 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
Length of Day Length of Day - Sunrise to Sunset 0 10 20 30 40 50 60 70 80 90 15 Jan 12.1 12.6 13.2 13.9 14.6 15.9 18.0 24.0 24.0 24.0 15 Feb 12.1 12.4 12.7 13.1 13.6 14.2 15.3 17.6 24.0 24.0 15 Mar 12.1 12.2 12.2 12.3 12.4 12.5 12.7 13.2 14.6 24.0 15 Apr 12.1 11.9 11.7 11.4 11.1 10.6 10 8.8 4.2 0 15 May 12.1 11.7 11.2 10.6 9.9 9.0 7.4 3.6 0 0 15 June 12.1 11.5 10.9 10.2 9.3 8.1 5.9 0 0 0 15 July 12.1 11.6 11.0 10.4 9.6 8.5 6.6 0 0 0 15 Aug 12.1 11.8 11.4 11 10.5 9.9 8.7 6.7 0 0 15 Sep 12.1 12.0 12.0 11.9 11.8 11.7 11.5 11.3 11.2 0 15 Oct 12.1 12.3 12.6 12.8 13.2 13.6 14.3 15.2 20.2 24.0 15 Nov 12.1 12.6 13.1 13.6 14.3 15.3 17.0 21.3 24.0 24.0 15 Dec 12.1 12.7 13.3 14.1 15.0 16.3 18.7 24.0 24.0 24.0
Solar Insolation (1) Solar insolation is the total energy received per unit area Insolation depends the average elevation angle of the sun during the day and is there also related to the length of the day For any location on earth this depends on season and latitude The sun tends to be at a lower elevation angle at high latitudes but this is offset by the longer day length during the summer season
Solar Insolation (2)
Angular Variation of Intensity Summer sun is high in the sky at noon f A S θ θ A G A G = A S /cos θ Winter Sun is low in the sky at noon
Refraction in the Atmosphere REFRACTION of sunlight by the Earth s Atmosphere Sunset horizon - apparant position of Sun Sunrise actual position of Sun atmosphere
An Extreme Case of Refraction