1. Cycles in Nature

2. Cycles in Nature
Many of the daily, monthly and seasonal changes that take place on Earth are patterns that occur over and over – Rhythms.
Types of Rhythms:
Day into night = daily rhythm
Rise and fall of tide = daily & monthly rhythms
Lunar phases = monthly rhythm
Changing of seasons – annual rhythm

3. Daily Rhythms Day/Night Cycles: Earth rotates (spins) on it’s axis
1 rotation – 1 day or 24 hours
spins from West to East
Sun rises in the East and sets in the West.
Half of the earth is always lit!
Earth’s Rotation Simulator

4. Affects of Daily Rhythms
Diurnal Eyes
Organisms adapt many of their daily activities around day/night cycles.
Diurnal = active during the day
Best suited for:
warm
dry
bright conditions
Nocturnal = active during the night
cool
moist
dark conditions
Very large eyes
Nocturnal Eyes
library.thinkquest.org/

5. Tides – Daily Rhythms
Earth has a natural satellite, the moon, that revolves (orbits) around it.
The moon has a gravitational pull that affects the location of water on Earth.
Tide Simulator

6. Tides
The Earth rotates, spins, once in 24 hrs which means that the Earth moves into and out of a tidal bulge once every 6 hours.
Creates:
2 high tides daily
2 low tides daily.

7. Tides – monthly rhythms
The moon revolves, orbits, around the Earth once every 27.3 days
Affect monthly tide cycles too.
If the moon is in a straight line with the sun and Earth it causes higher than normal high tides – Spring Tides.
Both the moon’s and sun’s gravitational pull are acting on Earth’s waters.
Full moon and New moon
If the moon is at a right angle to the Earth and sun it causes lower than normal high tides – Neap Tides.
The sun’s gravitational pull cancels out the moon’s gravitational pull.
1st Quarter and 3rd Quarter

8. Spring Tides

9. Neap Tides

10. The Moon – Monthly Rhythms
Moon revolves around the earth
Earth’s only satellite!
1 revolution – 1 month or 27.3 days
Moon also rotates on its axis
1 rotation = 27.3 days
Rotation = Revolutions
1 day = 1 year
Same side of the moon always faces the earth!

11. Moon’s Orbit
scssi.scetv.org/

12. Moon Phases
As the moon revolves around the earth the amount of lit surface, visible from earth, is always changing.
Waxing phases – lit surface is increasing
Light on the right!
Waxing Crescent
1st Quarter
Waxing Gibbous
Full Moon – full lit surface facing earth

13. Moon’s Phases
Waxing Phases
(Light on Right!)

14. Waxing Crescent
Light on the RIGHT

15. First Quarter Moon
Light on the RIGHT

16. Waxing Gibbous
Light on the RIGHT

17. Full Moon

18. Moon Phases Waning phases – lit surface is decreasing
Light on the left!
Waning Gibbous
3rd Quarter
Waning Crescent
New Moon – no lit surface facing earth

19. Moon’s Phases
Waning Phases
(Light on Left!)

20. Waning Gibbous
Light on the LEFT!

21. 3rd Quarter Moon
Light on the LEFT!

22. Waning Crescent
Light on the LEFT!

23. New Moon
Moon Phases Simulator

24. Annual Rhythms The Earth: Earth revolves around the sun
1 revolution – 1 year or 365 days
Earth is tilted on it’s axis – 23.5°
Seasons occur because of the direction of the tilt!

25. Seasons

26. Affects of Environmental Rhythms
Organisms can only survive in a habitat if all conditions needed for survival are met. As different cycles in nature start to affect an organism’s survival they need to either adapt or move.
Breeding Seasons
Hibernation
Estivation
Migration

27. Breeding Seasons
Organisms time the birth of offspring for when seasonal conditions are best for the survival of the offspring.
Longer gestation period: Pregnant through the more difficult seasons, fall & winter, and deliver when conditions are best, spring & summer.
Deer - Breed in fall and birth in spring
Shorter gestation period: Pregnant just as conditions are turning for the better and deliver as they reach their peak, spring & summer.
Geese – breed in spring and hatch in spring.

28. Hibernation & Estivation
Hibernation – sleep through the seasons that can’t support needs, winter months.
Bears & groundhogs
Estivation – spend the hottest and driest portion of the day inactive.
Snails, reptiles & lions

29. Migration
If organisms aren’t able to survive during difficult conditions they may move to better locations that can support their needs – Migration.
Hummingbirds, Monarch Butterflies, Wildebeest, Whales.

30. Environmental Cycles
The Earth also experiences natural cycles that affect the survival of organisms.
Water Cycle
Carbon/Oxygen
Nitrogen
Ecological Succession

31. Water Cycle 3/4th of the planet is cover by water
Water is continuously circulating between surface and atmosphere.
Not a predictable pattern but random.

32. Cycles in Nature Evaporation – liquid water to gas
Occurs with presence of heat
Condensation – gas to liquid droplets
Cooler conditions
Dew and formation of clouds
Precipitation – water falling back to earth
Rain, snow, sleet or hail
Infiltration - Water being absorbed into the soil
Groundwater – water being stored in the ground
aquifers
Runoff – freely flowing water on the ground.
Rivers, streams

33. Carbon/Oxygen
The exchange of carbon dioxide and oxygen between animals and plants.
Respiration:
O2 + Glucose = CO2 + H2O + Energy
Photosynthesis:
CO2 + H2O + Sunlight =
O2 + Glucose

34. Nitrogen Cycle 78% of the atmosphere is Nitrogen (N)
Needed by all living things but cannot be obtained through the air we breathe!
Nitrogen Fixation – bacteria use free nitrogen to make nitrogen compounds in the soil.
Nitrates can then be used by organisms when they eat plants.

35. Ecological Succession
The gradual long term changes in altered ecosystems.
Ecosystems tend to change until a stable system is formed.
The type of succession depends on climate (temperature & precipitation) and other limitations of a given area.
Can be sped up or slowed down
Sewage = aquatic plants grow faster
Plowing, fire, and floods = slow down succession
Succession Simulator

36. Stages of Ecological Succession
Pioneer organisms are the first organisms to reoccupy an area
grasses in a plowed field, lichens on rocks
Climax community - final stable community.
can last for hundreds or thousands of years.

37. Pioneer Organisms
Climax Community