ATMO 9/4 Skew-T, Humidity, and Dewpoint

Current Weather:
- TS Hannah forecasts are not so accurate, lingering around the Caribbean islands
- Hurricane Ike Cat 4, strengthened much more than forecasted and much quicker

Skew-T Diagram:
- Weather balloons (radiosondes) launched twice per day from various weather observing stations at 0000 UTC (00Z) and at 1200 UTC (12Z) (UTC = Universal time coordinated)
- Tucson local time is 7 hours earlier than UTC, so radiosondes are launching at 5PM the day before, and 5AM the day of
- #'s right of the y-axis are meters above sea level
- Barbs: Flags are 50 knots, long barbs are 10 knots, short barbs are 5 knots
- Wind Direction: Main post which barbs stick off of, points in the direction in which the wind is coming from. The barb shows the direction the wind is blowing toward the center (circle) of the symbol
- Surface temp changes much more than at 500mb (~5900ft) day to day

Water in the Atmosphere: Condensation and Evaporation
- Internal energy per gram of water (greatest to least): gas, liquid, ice
- The more energy the more unorganized the molecules become
- To go from a lower to a higher energy phase, you need to add energy to the water and vice versa
- Latent heat: energy added to or removed from water as it changes phase, there is no measurable change in the temperature of water
- Sensible heat: the energy added or removed from water that results in a temperature change
- Calorie: a unit of energy for measuring energy. 1 calorie= amount of energy to raise the temp of 1 gram of liquid water by 1C
- In dietary science: 1 dietary calorie = 1,000 scientific energy measurement calories
- 1g of ice at -100C takes 50 calories to raise it to 0C (sensible heating process, hasn't changed phase yet). Add 80 calories to the 1g of ice, you get 1g of liquid water at 0C (latent heating process, changed phases (melted)). Add 100 calories to the 1g of water, you get 1g of water at 100C (sensible heating process, water heated). Add 600 calories, you get 1g of water vapor (gas) at 100C (latent heating, phase change, no temp. Increase (evaporation). Reversing this process is done with the same amount of energy (calories) in reverse (removing energy or condensation, freezing).
- Phase changes from adding energy is supplied from surrounding environment. If the energy is supplied from the surrounding environment, the surrounding environment looses energy and cools. Example: Evaporating Sweat (energy supplied from your skin or the air around your skin, causing a cooling feeling)
- Phase changes from removing energy is supplied from the surrounding environment, causing the surrounding environment to heat up. Typically happens where clouds form via condensation and heating the air around the cloud.. - Evaporation cools the surrounding environment, condensation warms the surrounding environment.
- Evaporation and condensation can happen at any temperature between 0C and 100C

Vapor Pressure:
- The pressure caused by water molecules only, not any other elements
- The higher the vapor pressure, the more water molecules there are in the air

Rate of Evaporation:
- The number of water molecules that change phase from liquid to gas each second (or unit of time). Depends highly on the temp. at the liquid water surface, the higher the temp, the higher the rate.

Rate of Condensation:
- The number of water molecules that change phase from gas to liquid each second (or unit of time). Depends highly on the vapor pressure of the air above the liquid surface. The higher the vapor pressure, the higher the rate of condensation.