WELCOME TOAOS 101: WEATHER AND CLIMATE

Discussion Session

Lisha M. RoubertUniversity of Wisconsin-Madison

Department of Atmospheric & Oceanic Sciences

AOS 101 DISCUSSION/LAB

• Instructor: Lisha M. Roubert Office 1449 AO&SS bldg email: roubert@wisc.edu• Office Hours: T 1:00-2:30PM W 2:30-3:45PM *or by appointment• Discussion Session Website www.aos.wisc.edu/~roubert/aos_101_home.html

ABOUT YOU

• Name• Email• Year• Major• Weather and Climate Topics that you are interested

in.

AOS 101 DISCUSSION SCHEDULE

• Hand in Homework• Review of last week• Start new topic and lab exercise• Discussion-everyone must participate!

WEATHER VS. CLIMATE

• Get in groups and answer:Define weatherDefine climate

Weather is what’s happening outside.Climate is a long-term average of the Weather.

HOW DOES CLIMATE DIFFER FROM WEATHER?

•Weather- describes the state of the air at a particular place and time• Example: whether it is warm or cold, wet or dry, how

cloudy or windy it is.• Weather events are bound by the variables that exist

in Earth's atmosphere: temperature, air pressure, water vapor, the local amounts of and interactions between the variables, and how they change over time.

HOW DOES CLIMATE DIFFER FROM WEATHER?

•Climate- refers to the normal pattern of weather experienced in a particular area over a long period of time . The climate tells us how hot, cold or wet it is likely to be in different parts of the world at different times of year. • Example: tropical countries have hot climates and

the Antarctic has a cold climate.• The climate of a location is affected by its latitude,

terrain, and altitude, as well as nearby water bodies and their currents.

HOW DOES STATISTICS LINK WEATHER AND CLIMATE?

• The entire reason we have "climate zones" is that the weather follows statistical patterns over decades in those regions.

• We call "climate" the statistical trend of weather over long periods of time. We can statistically predict when the climate will be different.

HOW DO WE KNOW IF THE CLIMATE WILL BE DIFFERENT?

• The weather will be different due to the effects of different modes of climate variability. This will cause a change in the general climate of a region.

• A mode of climate variability is a pattern with identifiable characteristics that causes specific regional effects.

• Modes of climate variability are used by climatologists as indices.

• El Niño and La Nina are examples of modes of climate variability. El Niño is characterized by unusually warm temperatures and La Niña by unusually cool temperatures in the equatorial Pacific.

HOW DO WE KNOW IF THE CLIMATE WILL BE DIFFERENT?

• Three of the main things that cause the greatest effects on climate worldwide are:

-the seasonal cycle: caused by the movement of earth around the sun

-El Nino: it is caused by interactions between the atmosphere and the ocean

-Thermohaline circulation (THC): moves water between the deep and surface ocean worldwide. The water moves mainly because of differences in density. Water that is more dense sinks below water that is less dense.

• Among other modes of climate variability we know about are:

-The Madden–Julian oscillation (MJO) -The North Atlantic oscillation (NAO) -The Pacific decadal oscillation (PDO) and many more.

The Thermohaline circulation or Global Ocean Conveyor

WHAT APPROACHES ARE USED TO STUDY CLIMATE?

• Past climate (Paleoclimate)-past climate is studied by using records such as:

-ice cores-the composition of air in bubbles found in ice cores is analyzed to determine how the climate was in the past.

-tree rings- trees develop annual rings of different properties depending on weather, rain, temperature, CO2 concentration.

-geological proxy

WHAT APPROACHES ARE USED TO STUDY CLIMATE?

• Contemporary climate study-among the methods we have to study climate are:

- Data records-meteorological data accumulated over many years (Example: records of rainfall, temperature and atmospheric composition.)

- Climate models-models incorporate all the knowledge we have of the atmosphere and its dynamics. They can be used to demonstrate historic climate events, and also to forecast future events on the basis of information about the past. Climatologists can also manipulate their models to show how various changes can impact the future of the climate.

Map of the average temperature over 30 years. We can make these maps thanks to data records.

Climate models simulate the interactions of the atmosphere, oceans, and land surface so we can make predictions of future climate.

http://vis.lbl.gov/~prabhat/GFDL/

HOW WILL CLIMATE BE APPROACHED IN THIS COURSE?

• Statistical Analysis- You will learn to do different types of climate analysis on data in order to

find trends that reveal information about the climate of the location under study. It is important that you learn to use Microsoft Excel!

• Rotating Tank Lab - The rotating tank lab will be used occasionally to illustrate different

climate concepts.