What is weather?
What is Weather? <ul><li>Weather - referring to the present state of the atmosphere and describing current conditions </li...
Factors Of Weather <ul><li>Water cycle forms the basis of our weather </li></ul><ul><li>Sun is also very important </li></...
Humidity <ul><li>Humidity - amount of water vapor in air </li></ul><ul><li>The air is like a sponge </li></ul><ul><ul><li>...
Relative Humidity <ul><li>Relative Humidity - measure of the amount of water vapor air is holding in comparison with the a...
Dew Point <ul><li>Dew point – temperature at which air is saturated and condensation begins </li></ul><ul><ul><li>The dew ...
Clouds <ul><li>Formed when warm air travels up, expands and cools </li></ul><ul><ul><li>When air cools, the amount of wate...
Cloud Classification <ul><li>Many different types, all classified by shape and height </li></ul><ul><ul><li>3 main types: ...
Stratus <ul><li>Forms layers and appears as smooth sheets in the sky </li></ul><ul><li>Created when layers cool below dew ...
Cumulus <ul><li>Appears as puffy white clouds </li></ul><ul><ul><li>Often flat bases </li></ul></ul><ul><ul><li>Referred t...
Cirrus <ul><li>Appears as curly tendrils and fibers </li></ul><ul><ul><li>High, thin white feathery clouds </li></ul></ul>...
Cloud Height <ul><li>Prefixes are used to describe the height of a clouds base </li></ul><ul><ul><li>Cirro: high elevation...
Rain Capacity <ul><li>Nimbus~ dark clouds </li></ul><ul><ul><li>So full of water, no sunlight penetrates it </li></ul></ul...
Precipitation <ul><li>Precipitation – water falling from clouds </li></ul><ul><li>Temperature determines whether water fal...
Section Wrap Up <ul><li>When does water vapor in air condense? </li></ul><ul><li>How do clouds form? </li></ul><ul><li>How...
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What is weather

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What is weather

  1. 1. What is weather?
  2. 2. What is Weather? <ul><li>Weather - referring to the present state of the atmosphere and describing current conditions </li></ul><ul><ul><li>Important factors of weather : </li></ul></ul><ul><ul><ul><li>Air pressure </li></ul></ul></ul><ul><ul><ul><li>Wind </li></ul></ul></ul><ul><ul><ul><li>Temperature </li></ul></ul></ul><ul><ul><ul><li>Amount of moisture in the air (humidity) </li></ul></ul></ul><ul><ul><li>Factors of weather determine state of atmosphere </li></ul></ul>
  3. 3. Factors Of Weather <ul><li>Water cycle forms the basis of our weather </li></ul><ul><li>Sun is also very important </li></ul><ul><ul><li>Evaporates water </li></ul></ul><ul><ul><li>Heats air </li></ul></ul><ul><ul><ul><li>This causes wind motion by the interaction of air, water and sun </li></ul></ul></ul>
  4. 4. Humidity <ul><li>Humidity - amount of water vapor in air </li></ul><ul><li>The air is like a sponge </li></ul><ul><ul><li>Water vapor molecules fit in spaces between air molecules </li></ul></ul><ul><li>Humidity changes daily because the change in air temperature </li></ul><ul><ul><li>Temperature determines the amount of water vapor that the air can hold </li></ul></ul><ul><ul><ul><li>Cooler temperatures: air moves slower </li></ul></ul></ul><ul><ul><ul><ul><li>Allows water molecules to join and condense </li></ul></ul></ul></ul><ul><ul><ul><li>Warmer temperatures: air moves faster </li></ul></ul></ul><ul><ul><ul><ul><li>No time for water to condense, stays a vapor </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Hotter, damper, and holds more water vapor </li></ul></ul></ul></ul></ul>
  5. 5. Relative Humidity <ul><li>Relative Humidity - measure of the amount of water vapor air is holding in comparison with the amount it can hold at a certain temperature </li></ul><ul><li>Saturated – air containing all the moisture possible for its temperature </li></ul><ul><ul><li>Ex. If weather reporter says the relative humidity is 70%, then it needs 30% more to be saturated </li></ul></ul>
  6. 6. Dew Point <ul><li>Dew point – temperature at which air is saturated and condensation begins </li></ul><ul><ul><li>The dew point will change with the amount of moisture in the air </li></ul></ul><ul><ul><ul><li>Ex. A cold glass of milk will cool surrounding air to its dew point causing water droplets from surrounding air to form onto cup </li></ul></ul></ul>
  7. 7. Clouds <ul><li>Formed when warm air travels up, expands and cools </li></ul><ul><ul><li>When air cools, the amount of water vapor needed for saturation goes down and relative humidity increases </li></ul></ul><ul><ul><li>When air is saturated (100% relative humidity) then water vapor condenses around nuclei </li></ul></ul><ul><ul><ul><li>Small particles of dust, salt and smoke in the atmosphere </li></ul></ul></ul><ul><ul><ul><li>Water molecules are so small they remain suspended within the air </li></ul></ul></ul><ul><ul><ul><ul><li>Millions of these water molecules form a cloud </li></ul></ul></ul></ul>
  8. 8. Cloud Classification <ul><li>Many different types, all classified by shape and height </li></ul><ul><ul><li>3 main types: </li></ul></ul><ul><ul><ul><li>Stratus </li></ul></ul></ul><ul><ul><ul><li>Cumulus </li></ul></ul></ul><ul><ul><ul><li>Cirrus </li></ul></ul></ul>
  9. 9. Stratus <ul><li>Forms layers and appears as smooth sheets in the sky </li></ul><ul><li>Created when layers cool below dew point </li></ul><ul><ul><li>In low altitudes </li></ul></ul><ul><li>Associated with fair weather and precipitation </li></ul><ul><li>Sometimes seems like a dull gray blanket covering the sky </li></ul><ul><ul><li>Brings drizzle </li></ul></ul><ul><li>When cooled near ground it is called fog </li></ul>
  10. 10. Cumulus <ul><li>Appears as puffy white clouds </li></ul><ul><ul><li>Often flat bases </li></ul></ul><ul><ul><li>Referred to as “cauliflower” clouds </li></ul></ul><ul><ul><li>May be very high in length </li></ul></ul><ul><li>Formed when air current rises </li></ul><ul><li>Associated with fair weather and thunderstorms </li></ul>
  11. 11. Cirrus <ul><li>Appears as curly tendrils and fibers </li></ul><ul><ul><li>High, thin white feathery clouds </li></ul></ul><ul><li>Contains ice crystals </li></ul><ul><li>Associated with fair weather, may indicate approaching storm </li></ul>
  12. 12. Cloud Height <ul><li>Prefixes are used to describe the height of a clouds base </li></ul><ul><ul><li>Cirro: high elevation, above 6000m </li></ul></ul><ul><ul><li>Alto: middle elevation, between 2000-6000m </li></ul></ul><ul><ul><li>Strato: low elevation, below 2000m </li></ul></ul>
  13. 13. Rain Capacity <ul><li>Nimbus~ dark clouds </li></ul><ul><ul><li>So full of water, no sunlight penetrates it </li></ul></ul><ul><ul><li>Nimbus that is also a cumulus cloud is called a cumulonimbus </li></ul></ul><ul><ul><ul><li>These grow huge </li></ul></ul></ul><ul><ul><ul><li>Can be up to 18000m </li></ul></ul></ul><ul><ul><ul><li>May produce violent thunderstorms </li></ul></ul></ul><ul><ul><ul><li>When water droplets become .2mm they fall </li></ul></ul></ul><ul><ul><ul><ul><li>too heavy </li></ul></ul></ul></ul>
  14. 14. Precipitation <ul><li>Precipitation – water falling from clouds </li></ul><ul><li>Temperature determines whether water falls as : </li></ul><ul><ul><li>Rain; drops of water falling above freezing </li></ul></ul><ul><ul><li>Snow; drops below freezing, turn directly to solid </li></ul></ul><ul><ul><li>Sleet; when snow passes through a warm layer and melts, then refreezes near the ground </li></ul></ul><ul><ul><li>Hail; form of ice, they grow larger when they fall up and down (because of convection current) </li></ul></ul><ul><ul><ul><li>Most smaller than 25cm </li></ul></ul></ul><ul><ul><ul><li>Produced the most damage </li></ul></ul></ul>
  15. 15. Section Wrap Up <ul><li>When does water vapor in air condense? </li></ul><ul><li>How do clouds form? </li></ul><ul><li>How can the same cumulonimbus cloud produce both rain and hail? </li></ul>

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