1 / 21

Moisture

Moisture. States of Water. 3 states of water: Solid (Ice) -Liquid (water) -Gas (water vapor) Transformations To more energetic state: Evaporation Melting Sublimation To less energetic state: Freezing Condensation Deposition. Latent Heat Absorbed. Latent Heat Released.

jude
Download Presentation

Moisture

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Moisture

  2. States of Water • 3 states of water: • Solid (Ice) -Liquid (water) -Gas (water vapor) • Transformations • To more energetic state: • Evaporation • Melting • Sublimation • To less energetic state: • Freezing • Condensation • Deposition Latent Heat Absorbed Latent Heat Released

  3. Hydrosphere: The realm of water in all its forms • Most water in oceans 97.5% • Most fresh water in glaciers • Much more ground water than fresh surface water • Very little in atmosphere at any one time

  4. Global Water Balance • Only a finite amount of water in Earth system • Precipitation into oceans= 380 cu km annually • Runoff from land into oceans= +40 cu km “ • Evaporation from oceans = 420 cu km “ • Precipitation onto land = 110 cu km “ • Runoff from land into oceans= - 40 cu km “ • Evaporation from land = 70 cu km “

  5. Humidity • Amount of water vapor in the air • Humidity varies dramatically all over Earth • Warm air can hold much more water vapor than cold air • Specific Humidity (SH) – actual quantity of water vapor in air • SH = mass of water vapor / mass of total air

  6. Saturation Specific Humidity • Saturation – when air can hold no more H2O↑ • When SH = Saturation SH • Increases geometrically with temperature

  7. Dew Point Temperature • Temp at which air, when cooled, becomes saturated • Provides measure of actual moisture in air • Curve is same as for saturation specific humidity • Also, a measure of human comfort • Dew point temp > 70°F considered oppressive

  8. Relative Humidity • What TV weather forecasters mean by “humidity” • H2O↑ in air compared to max H2O↑at that temp • Relative Humidity (RH) • RH = 100 X (SH / Saturation SH) • 50% RH means air has ½ max H2O↑ at that temp • RH can change by: • evaporation - condensation - change in temp.

  9. What is Heat? • As air rises, it expands and cools

  10. Adiabatic Process • The idea is that with a parcel of gas if no energy is added or subtracted, the temperature will rise if it is compressed, and fall if it expands • As air rises in the atmosphere, it expands and cools (since the air pressure drops) • As air falls in the atmosphere, is contracts and heats (Sana Anna winds, Chinooks)

  11. Adiabatic Process Air parcels cool at predictable rate as they rise: • Unsaturated (no condensation) • Dry adiabatic lapse rate (DAR)- 10°C/1000m • At lifting condensation level, saturation occurs • Saturated (condensation occurring, heat released) • Cloud forms as parcel rises • Moist adiabatic lapse rate – 4-9°C/1000m • Use 5°C/1000m as estimate of Moist adiabatic rate

  12. Precipitation Processes • Air expands & cools as it rises, but… • What makes it rise? • 4 processes help air to rise and drive precipitation • Orographic precipitation • Convective precipitation • Frontal precipitation • Convergence

  13. Orographic Precipitation • Moist air forced by wind over mtns • As air is lifted, condensation & precipitation occur • Air passes mtn top & descends leeward side • This air is compressed and warms with no precipitation • The dry, leeward side is called a Rainshadow

  14. Orographic Precipitation

  15. Convective Precipitation • Air pockets warm at surface & rise rapidly • As they rise, they cool, first at DALR 10°C/1000m • If ELR is high, air bubble stays warmer & rises • Bubble reaches dew point temp → condensation • Condensation forms clouds, releases heat • Air cools at MALR, averaging 5°C/1000m • Bubble cooling much slower than surrounding air • Bubble pushes high into troposphere

  16. Convective Precipitation Example

More Related