NATS 101 Lecture 3 Climate and Weather

Climate and Weather “Climate is what you expect. Weather is what you get.” -Robert A. Heinlein

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

Surface Station Model Temperatures Plotted  F in U.S. Sea Level Pressure Leading 10 or 9 is not plotted Examples: plotted as plotted as plotted as 360 Ahrens, p 431 Responsible for boxed parameters

Sky Cover and Weather Symbols Ahrens, p 431

Pressure Tendency Change in pressure over the past 3 hours is also plotted. Also called barometric tendency Ahrens, p 432

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

temperature dew point SLP pressure wind cloud cover Ohio State website

Practice Surface Station Temperate ( o F) Pressure (mb) Last Three Digits (tens, ones, tenths) Dew Point (later) Moisture Wind Barb Direction and Speed Cloud Cover Tenths total coverage Ahrens, p Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

Practice Surface Station Sea Level Pressure Leading 10 or 9 is not plotted Examples: plotted as plotted as plotted as 360 Ahrens, p Decimal point What are Temp, Dew Point, SLP, Cloud Cover, Wind Speed and Direction?

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

Radiosonde Weather balloons, or radiosondes, sample atmospheric to 10 mb. They measure temperature moisture pressure They are tracked to get winds Ahrens, Fig. 1

Radiosonde Distribution Radiosondes released at 0000 and at 1200 GMT for a global network of stations. Large gaps in network over oceans and in less affluent nations. Stations ~400 km apart over North America

Radiosonde for Tucson Example of data taken by weather balloon released over Tucson Temperature (red) Moisture (green) Winds (white) Note variations of all fields with height UA Tucson 1200 RAOB troposphere stratosphere tropopause temperature profile moisture profile wind profile

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

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)

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

Average and Record MAX and MIN Temperatures for Date

Climate of Tucson Probability of Last Freeze Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Probability of Rain Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Extreme Rainfall Cool Site: Western Region Climate CenterWestern Region Climate Center

Climate of Tucson Snow! Cool Site: Western Region Climate CenterWestern 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

Reading Assignment Ahrens Pages Problems (2.1  Chapter 2, Problem 1) Don’t Forgot the 4”x 6” Index Cards…