Water in the atmosphere

1. Water in the atmosphere

2. How does water get into the atmosphere? EVAPORATION process when fast-moving molecules of water can escape from liquid water into the surrounding air as gas or water vapor WATER GETS into the atmosphere

3. For the following pair of pictures, answer the following questions: • Which has faster evaporation – 1 or 2? • Explain why • Name the condition that speeds up evaporation Water gets into the atmosphere

4. Water gets into the atmosphere Evaporation increases as temperature increases

5. Evaporation requires a supply of ENERGY. HEAT= ENERGY Water gets into the atmosphere

6. Water gets into the atmosphere Evaporation increases as humidity decreases

7. Vapor Pressure is greatest then Net Evaporation becomes zero NET EVAPORATION= ZERO Water gets into the atmosphere

8. Water gets into the atmosphere Evaporation increases as surface area increases

9. Evaporation takes place on the SURFACE. WIDER SURFACE= MORE EVAPORATION Water gets into the atmosphere

10. The OCEANS of the earth evaporate about 10.5 million m3 of water every second Water gets into the atmosphere

11. Water gets into the atmosphere Evaporation increases as wind speed increases

12. Evaporation is affected by WIND. WIND = BLOWN WATER VAPOR Water gets into the atmosphere

13. Air containing much water vapor is HUMID Humidity = amount of water vapor in the air HUMIDITY increases as EVAPORATIONincreases HUMIDITY

14. The relationship of the amount of water vapor actually present in air to its capacity, expressed in percent, is Relative Humidity Relative humidity of 80% means that the actual water vapor in the air is 80% of its capacity at its temperature. The air at this temperature can absorb 20% more water vapor. relative HUMIDITY

15. MEASURING relative HUMIDITY • Two thermometers will be used: • Dry-bulb -> measures the air temperature • Wet-bulb -> measures the temperature of air cooled to capacity

16. MEASURING relative HUMIDITY

17. Solve for the Relative Humidity at different times of March 4, 1981. MEASURING relative HUMIDITY

18. Air with less than 100% relative humidity can be made to reach 100% by: • Evaporating enough water to the air without changing the air temperature. • Cooling or lowering the air temperature without changing the amount of water vapor in the air. Water vapor changes to water

19. Air must have a relative humidity of 100% for condensation to take place. Laboratory experiments show that when the solid particles normally present in air are removed, relative humidity sometimes reaches higher than 100%, sometimes as high as 400% before condensation begins. SUPERSATURATED - Air contains much more water vapor than it normally can hold Water vapor changes to water

20. Condensation Nuclei • Tiny solid particles in air needed to provide the surfaces on which water vapor collects to start condensation. • Sodium chloride • Fine ash • Dust • Plant spores • Pollen Water vapor changes to water

21. Formed by condensation clouds

22. Dry Air • Unsaturated rising air • Cools by 1C° for every 100m rise in altitude clouds

23. clouds

24. Saturated air begins to condense • Height varies with humidity • If humidity is high, air will begin to condense at less than a kilometer above the ground. • If humidity is low, air will rise higher before condensation begins. • Condensation at a height is seen from the ground as CLOUDS clouds

25. Types of Clouds Cumulus Stratus Cirrus Nimbus Fog clouds

26. Cumulus clouds • Formed by warm rising air • Appear like piles of puffed cotton • Indicates fair weather

27. Formed when a whole layer of high humidity air either absorbs more water vapor or cools enough to begin condensation Often gray in appearance Low-lying but do not touch the ground Stratus clouds

28. Air that condenses while in contact with the ground fog

29. Cirrus clouds • Highest clouds • Formed from air of low humidity • Often has to rise higher than 6000 m to reach condensation temperature which occurs at or below 0°C • Appear as white, feathery streaks

30. Thick, dark and rain-producing clouds Nimbus clouds

31. Prefix alto- • When either stratus or cumulus clouds form anywhere from 2 to 6 km above the ground • altocumulus and altostratus • Prefix cirro- • When either stratus or cumulus clouds form at 6 km altitude or higher • cirrostratus and cirrocumulus clouds

32. Clouds

33. Cloud Droplets • So tiny and light that they can remain in the air • May combine to form bigger drops that may fall as rain • May evaporate before reaching the ground • Should have a diameter of more than 0.1 mm to reach the ground in still air Water returns to the earth’s surface

34. Precipitation • Process by which condensed water vapor falls from the clouds to the ground. Water returns to the earth’s surface

35. Cloud seeding • Artificial rain • Done by dropping dry ice (CO2 at -78.5 °C) into clouds from an airplane • Other methods of producing rain • Silver iodide • Table salt • Urea • Seawater Water returns to the earth’s surface

36. PAGASA (Philippine Atmospheric, Geophysical, Astronomical Services Administration) Weather and climate

37. Some Terms PAGASA use in Forecasting General Weather Fine Weather or Sunny - no precipitation or clouds expected Fair weather – favorable weather for ordinary activities; precipitation may be expected but only in small amounts and of short duration Warm – temperatures expected to exceed 32°C Cool – temperatures expected to be below 21°C Humid – relative humidity expected to be above 90% Weather and climate

38. Some Terms PAGASA use in Forecasting General Weather Windy or Gusty – winds expected to blow about 18km/hr or faster Squally – winds over 27km/hr and generally accompanied by intermittent rain Stormy Weather – high winds of about 64-118km/hr associated with precipitation and sometimes thunderstorms Unsettled – cloudiness with some rain Weather and climate

39. Some Terms PAGASA use in Forecasting General Weather Rainy – rain from nimbostratus, cumulonimbus, cumulus, stratocumulus, or altostratus clouds with drops larger than 0.5mm Drizzle – numerous small drops less than 0.5mm fall from fog or stratus clouds Shower – rain of short duration over a small area Thunderstorm – storm accompanied by thunder and lightning Weather and climate

40. Weather Forecast • Reports on the expected general condition of the atmosphere in the next 24 hours based on the observed temperature, cloudiness, wind direction, and wind strength of the proceeding 24 hours. • Some weather forecasts include observations on relative humidity, air pressure, and air fronts. Weather and climate

41. Does not change much due to the movement of vertical rays from the sun. Sun’s vertical rays sweep northward over the Philippines from April 3 to May 26 and southward from July 19 to September 10 May 26 to July 19 is too short to cool the land which makes May to September one long warm period. Air temperature in the Philippines

42. rainfall in the Philippines

43. Mountains Factors that affect rainfall

44. Begins as a low pressure center over an ocean with strong circulating winds. • Area of calm • Center of a cyclone • Winds less than 24 km/hr and in some cases, no winds at all. • Eye • Where warm air rises in this area of calm Tropical cyclones

45. Classification of Tropical Cyclones Depression – wind speed less than 60 km/hr Storm – 60-118 km/hr wind speed Typhoon – wind speed is 119 km/hr or more Tropical cyclones

46. Tropical cyclones

47. Instruments used to determine Cyclones Barometers Anemometer => 1 knot = 1.85 km/hr Satellites Radar (radio detecting and ranging) Tropical cyclone

48. PAGASA’s System of Warning Signals Tropical cyclone

49. Strong winds, short-period heavy rains that generally last for one or two hours, lightning, and thunder thunderstorms

50. Where northeast and southeast trade winds meet Moves north or south of the equator with the summer season Inter tropical convergence zone (ITCZ)