Weather, Climate & Society ATMO 336 Climate vs. Weather

“Climate is what you expect. Weather is what you get.” Climate and Weather “Climate is what you expect. Weather is what you get.” -Robert A. Heinlein Lecture 2-Nats 101

Weather Weather – The state of the atmosphere: for a specific place at a particular time Weather Elements 1) Temperature 2) Pressure 3) Humidity 4) Wind 5) Visibility 6) Clouds 7) Significant Weather Lecture 2-Nats 101

Responsible for boxed parameters Surface Station Model Responsible for boxed parameters Temperatures Plotted F in U.S. Sea Level Pressure Leading 10 or 9 is not plotted Examples: 1013.8 plotted as 138 998.7 plotted as 987 1036.0 plotted as 360 Ahrens, p 431 Lecture 2-Nats 101

Sky Cover and Weather Symbols Ahrens, p 431 Ahrens, p 431 Lecture 2-Nats 101

Wind Barbs Direction Wind is going towards Westerly  from the West Speed (accumulated) Each flag is 50 knots Each full barb is 10 knots Each half barb is 5 knots 65 kts from west Ahrens, p 432 Lecture 2-Nats 101

Ohio State website SLP pressure temperature dew point cloud cover wind Lecture 2-Nats 101 wind

Practice Surface Station Temperate (oF) Pressure (mb) Last Three Digits (tens, ones, tenths) Dew Point (later) Moisture Wind Barb Direction and Speed Cloud Cover Tenths total coverage Ahrens, p 431 72 58 111 Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction? Lecture 2-Nats 101

Practice Surface Station Sea Level Pressure Leading 10 or 9 is not plotted Examples: 1013.8 plotted as 138 998.7 plotted as 987 1036.0 plotted as 360 Ahrens, p 431 42 18 998 Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction? Lecture 2-Nats 101

Surface Map Symbols Fronts Mark the boundary between different air masses…later Significant weather occurs near fronts Current US Map Ahrens, p 432 Lecture 2-Nats 101

Responsible for boxed parameters Upper-Air Model Responsible for boxed parameters Conditions at specific pressure level Wind Temperature (C) Moisture (Later) Height above MSL UA 500mb Analysis Ahrens, p 431 Ahrens, p 427 Lecture 2-Nats 101

Climate Climate - Average weather and range of weather, computed over many years. Whole year (mean annual precipitation for Tucson, 1970-present) Season (Winter: Dec-Jan-Feb) Month (January rainfall in Tucson) Date (Average, record high and low temperatures for Jan 1 in Tucson) Lecture 2-Nats 101

Lecture 2-Nats 101

Lecture 2-Nats 101

Climate of Tucson Monthly Averages Individual months can show significant deviations from long-term, monthly means. Lecture 2-Nats 101

Lecture 2-Nats 101

Climate of Tucson Probability of Rain Lecture 2-Nats 101 Cool Site: Western Region Climate Center

Climate of Tucson Extreme Rainfall Lecture 2-Nats 101 Cool Site: Western Region Climate Center

Cool Site: Western Region Climate Center Climate of Tucson Snow! Lecture 2-Nats 101 Cool Site: Western Region Climate Center

Summary Weather - atmospheric conditions at specific time and place Weather Maps  Instantaneous Values Climate - average weather and the range of extremes compiled over many years Statistical Quantities  Expected Values Lecture 2-Nats 101

Weather, Climate & Society ATMO 325 Global Energy Balance Greenhouse Effect

General Laws of Radiation All objects above 0 K emit radiant energy Hotter objects radiate more energy per unit area than colder objects Stefan-Boltzman Law The hotter the radiating body, the shorter the wavelength of maximum radiation Wien’s Displacement Law Objects that are good absorbers of radiation are also good emitters Lecture 2-Nats 101

General Laws of Radiation Wien’s Displacement Law Stefan-Boltzman Law Lecture 2-Nats 101

Sun - Earth Radiation Spectra Ahrens, Fig. 2.8 Planck’s Law Lecture 2-Nats 101

Absorption Visible (0.4-0.7 m) is absorbed very little IR Visible (0.4-0.7 m) is absorbed very little O2 an O3 absorb UV (shorter than 0.3 m) Infrared (5-25 m) is selectively absorbed H2O & CO2 are strong absorbers of IR Little absorption of IR around 10 m Ahrens, Fig. 2.9 Lecture 2-Nats 101

Total Atmospheric Absorption Ahrens, Fig. 2.9 Visible radiation (0.4-0.7 m) is not absorbed Infrared radiation (5-25 m) is selectively absorbed, but there is an emission window at 10 m Lecture 2-Nats 101

1 Unit Outgoing IR to Space 2 Units IR Emitted by Ground Greenhouse Effect: Simple Example (1-layer atmo., 100% IR, 0% SR absorbed) Balance 1 Unit Outgoing IR to Space 1 Unit Incoming Solar 1/2 1/4 1/8 1/16 ½ emitted to space ½ emitted to ground no SR absorbed all IR absorbed All SR +IR absorbed 1 1/2 1/4 1/8 1/16 2 Units IR Emitted by Ground Net effect is 1 extra unit absorbed by the ground! Lecture 2-Nats 101

Global Solar Radiation Balance 70% solar absorbed by earth-atmosphere Ahrens, Fig. 2.13 Lecture 2-Nats 101

The Atmosphere is Heated from Below Ahrens, Fig. 2.11 old ed. Lecture 2-Nats 101

Global Atmo Energy Balance Ahrens, Fig. 2.14 Lecture 2-Nats 101

Summary Greenhouse Effect (It’s a Misnomer) Energy Balance Warmer than Rad. Equilibrium Temp Reason: selective absorption of air H2O and CO2 most absorbent of IR Energy Balance Complex system All modes of Heat Transfer are important Lecture 2-Nats 101