AOS 101 Weather and Climate Lisha M. Roubert University of Wisconsin-Madison Department of Atmospheric & Oceanic Sciences

Global Air Temperatures from What can you observe in the temperature patterns during a year: January to December?

Why do temperatures shift throughout the year? Seasonal Variations-caused by earth’s tilt and the rotation of Earth around the sun. Earth is tilted 23.5 degrees respect to it’s axis of rotation. This tilt causes the different hemispheres to be at different angles to the sun at different times of year. Axis of rotation 23.5◦

Global Temperatures What can you observe in regards to the temperatures in the equator throughout a year? Average July Temperature Average January Temperature

Why are temperatures in the equator warm year round? Latitude-locations near the equator don’t experience much seasonal variations. Due to the earth’s tilt the sun always directly illuminates the equator and for this reason it is warm all year round. Northern Hemisphere Winter Northern Hemisphere Summer

Summary Seasonal variations cause shifts in temperature in the northern and southern hemisphere. Latitude determines how marked seasons will be. The closer you are to the equator: - the more warm it will be - there will be less variation in seasons

Madison, WI Located in the Northern Hemisphere at a latitude of 43° 4′ 0″ N. It is a region of variable weather patterns. Climate in the region is temperate with very large seasonal variations. During the winter temperatures are well below freezing with moderate to occasionally heavy snowfall. In the summer temperatures average in the lower 80˚F and can reach 90˚F.

Are Temperatures in Wisconsin changing? Most of Wisconsin has warmed since 1950, on average the increase in temperature is of 1.1˚F. Northwest Wisconsin has experienced the greatest increase in temperature, ˚F. “Wisconsin is becoming less cold with the greatest warming during winter- spring and nighttime temperatures increasing more than daytime temperatures” -WICCI The average increase in temperature for Madison has is between ˚F

What can we expect for Wisconsin in the future? It has been projected that Wisconsin will warm by 4- 9°F by the middle of this century. ▫Northern Wisconsin is projected to warm the most. ▫The least warming is expected along Lake Michigan. This mean projected warming rate is about four times greater than what has been observed since We can expect an increase in temperatures of approx. 6.5˚F for Madison Projected Change in Annual Average Temperature (°F) from 1980 to 2055

Studying Madison, WI Temperature Trends Today you will study temperature trends in Madison throughout the years using all the information you’ve learned in this class. You will be calculating: ▫mean-average value of the data ▫median-numeric value that separates the higher half of the data from the lower half of the data ▫standard deviation-measure of the spread in the data You will also determine the effect that removing the seasonal cycle has on the data.