Weather & Climate: The Sun, Earth, and Precipitation

1. Weather & Climate Chapter 3

2. Section 1: Weather & Climate • Weather& Climate 1. Weather - the condition of the bottom layer of the earth’s atmosphere in one place over a short period of time - temperature, moisture, precipitation, wind 2. Climate – the weather patterns in an area over a long period of time ***Usually described in Temperature & Precipitation**** - depends on elevation, latitude, location of nearby landforms & bodies of water, wind & ocean currents *** Climate is what you expect, weather is what you get!!

3. The Sun & the Earth 1. The Greenhouse Effect a. Enough solar radiation reaches earth’s surface to warm air & water b. Atmosphere prevents heat from escaping back into space too fast (similar to glass walls & roof on a greenhouse) – allows warmth for plants to grow

4. SECTION 1 The Sun’s energy reaches Earth Half of the energy is reflected back into space or absorbed by the atmosphere. The other half is absorbed by Earth’s surface and converted into heat energy. The atmosphere traps this heat in a process called the greenhouse effect. The greenhouse effect helps keep the planet warm. Factors Affecting Climate The Sun’s Effect on Earth

5. c. Global Warming – a rise in earth’s temp. caused by  amts of CO2 & other substances – earth’s atmosphere traps heat from sun & reflects it back to earth. As gasses build up in atm., more heat trapped, global temps rise. - occurs naturally or by human action

6. * Global Warming could… - partially melt ice caps causing rise in ocean level + flooding of low-lying areas - increase precipitation in some areas/decrease it in others

8. SECTION 1 Mercury Earth Uranus Pluto Venus Mars Neptune The Solar System Jupiter Saturn Sun

9. 2. Rotation & Revolution a. Rotation = the spinning motion of the earth (like a top) 1) earth completes 1 rotation in 24 hrs 2) daytime – side that faces sun 3) nighttime – side facing away from sun

10. b. Revolution = 1 complete orbit of the earth around the sun 1) 1 revolution = 365 ¼ days 2) 4 x ¼ days = leap year c. earth tilted on axis 23 ½º 1) “tropics” receive most direct sunlight 2) because of tilt, sunlight strikes diff. parts of earth more directly at diff times of yr. 3) when North Pole tilted toward sun, northern hemisphere receives most direct sunlight. When SP tilted toward sun, southern hemisphere receives most direct sun

11. 4) these changes in SEASONS are solstices – either of the 2 times of yr when the sun appears directly overhead at the Tropics of Cancer 23 ½ºN /Capricorn 23 ½ºS 5) Equinox – either of the 2 times/yr when day & night are of nearly = length everywhere on earth – sun appears directly overhead equator

12. Reason for the seasons

13. Precipitation 1. Precipitation vs. Humidity a. Humidity – amt of water vapor in atmosphere b. Precipitation – all forms of water that fall from the atmosphere to earth’s surface 1) forms as air temp changes - warm, less-dense air absorbs more moisture than cool - when air cools, can’t retain water vapor, so condenses as liquid cools 2) occurs when more water collects in clouds than they can hold

14. Forms of Precipitation

15. The Water Cycle

16. 2. Types of Precipitation a. Convectional Precipitation - occurs when hot, humid air rises from the earth’s surface, cools, loses ability to hold water - common at equator/tropics b. Orographic Precipitation – occurs when warm, moist air forced upward over high landforms (RAINSHADOW) - common on seacoasts - warm winds cool as they rise over mt clouds form, rain/snow - air cool & dry on other side of mt *** Cascades/Sierra Nevadas

17. Rainshadow

18. c. Frontal Precipitation – (most common) – occurs when 2 fronts (air masses of diff. temps) meet. Warm air forced up by heavier, cooler air. As rising warm air cools, frontal precipitation forms