Mathematical Nature Walk

can we see farther in rain than in fog? 72 Q.44: How far away does that "road puddle" mirage appear to be? 73 Q.45: Why is the sky blue? 77 Q.46: So how much more is violet light scattered than red? 79 Q.47: What causes variation in colors of butterfly wings, bird plumage, and oil slicks? 80 Q.48: What causes the metallic colors in that cloud? 84 Q.49: How do rainbows form? And what are those fringes underneath the primary bow? 85 Q.50: What about the secondary rainbow? 92 Q.51: Are there higher-order rainbows? 93 Q.52: So what is that triple rainbow? 95 Q.53: Is there a "zeroth"-order rainbow? 98 Q.54: Can bubbles produce "rainbows"? 99 Q.55: What would "diamondbows" look like? 100 Q.56: What causes that ring around the Sun? 101 Q.57: What is that shaft of light above the setting Sun? 109 Q.58: What is that colored splotch of light beside the Sun? 111 Q.59: What's that "smiley face" in the sky? 113 Q.60: What are those colored rings around the shadow of my plane? 116 Q.61: Why does geometrical optics imply infinite intensity at the rainbow angle? 118 IN THE NEST 122 Q.62: How can you model the shape of birds' eggs? 122 Q.63: What is the sphericity index? 123 Q.64: Can the shape of an egg be modeled trigonometrically? 124 Q.65: Can the shape of an egg be modeled algebraically? 127 Q.66: Can the shape of an egg be modeled using calculus? 130 Q.67: Can the shape of an egg be modeled geometrically? 134 IN (OR ON) THE WATER 137 Q.68: What causes a glitter path? 137 Q.69: What is the path of wave intersections? 140 Q.70: How fast do waves move on the surface of water? 141 Q.71: How do moving ships produce that wave pattern? 148 Q.72: How do rocks in a flowing stream produce different patterns? 152 Q.73: Can waves be stopped by opposing streams? 154 Q.74: How far away is the storm? 157 Q.75: How fast is the calm region of that "puddle wave" expanding? 158 Q.76: How much energy do ocean waves have? 160 Q.77: Does a wave raise the average depth of the water? 162 Q.78: How can ship wakes prove the Earth is "round"? 164 In the forest 168 Q.79: How high can trees grow? 168 Q.80: How much shade does a layer of leaves provide for the layer below? 172 Q.81: What is the "murmur of the forest"? 174 Q.82: How opaque is a wood or forest? 176 Q.83: Why do some trees have "tumors"? 179 IN THE NATIONAL PARK 183 Q.84: What shapes are river meanders? 183 Q.85: Why are mountain shadows triangular? 189 Q.86: Why does Zion Arch appear circular? 191 IN THE NIGHT SKY 194 Q.87: How are star magnitudes measured? 194 Q.88: How can I stargaze with a flashlight? 196 Q.89: How can you model a star? 197 Q.90: How long would it take the Sun to collapse? 205 Q.91: What are those small rings around the Moon? 207 Q.92: How can you model an eclipse of the Sun? 210 AT THE END ... 217 Q.93: How can you model walking? 217 Q.94: How "long" is that tree? 221 Q.95: What are those "rays" I sometimes see at or after sunset? 224 Q.96: How can twilight help determine the height of the atmosphere? 228 Appendix 1: A very short glossary of mathematical terms and functions 231 Appendix 2: Answers to questions 1-15 234 Appendix 3: Newton's law of cooling 238 Appendix 4: More mathematical patterns in nature 240 References 243 Index 247

phenomenon. Adam particularly highlights the importance in this process of solving inverse problems. Ordinary math becomes adventure."--Booklist "If you are a walker, as I am, your daypack probably contains sunscreen, a poncho, a floppy hat, and a pair of binoculars. After reading this snappy guide to the mathematics of the outdoors, by John Adam, a professor of mathematics at Old Dominion University in Virginia, you might consider tossing in a programmable calculator... A sharp eye and an ingenious mind are at work on every page... Read this book with pencil and paper in hand. Then go forth, enjoy the view, and impress your friends."--Natural History "There are now few (if any) areas of science where mathematics does not play a role and, by extension, many of the sights and sounds of nature can be studied using mathematics. This is the motivation behind A Mathematical Nature Walk by John Adam, which considers some of the natural phenomena that might be encountered on a walk in the countryside (or even just a wander around one's own garden)."--Sarah Shepherd, iSquared "[S]urprising and entertaining... Adam's book is lucidly written, making it suitable for people of all ages."--Good Book Guide "The dedicated reader stands a lot to gain from delving into the text and thinking hard about the problems posed. As the saying goes, 'mathematics is not a spectator sport,' so if this book is read with pencil and paper at hand, to scribble along and confirm understanding of the mathematical trains of thought--all the better."--Philip McIntosh, Suite101.com