MET1010 Chapter 4

Hydrologic Cycle

Unending circulation of our water supply

Over the ocean, there is a (greater/lower) rate of evaporation than precipitation. On the land, there is a (greater/lower) rate of evaporation than precipitation. What compensates for the difference?

Greater;Lower. Runoff compensates for the difference

Vapor Pressure

that part of the total pressure due to water vapor molecules(mb)

What is the standard pressure at sea level?

1013 millibars

Humidity

Measure of water vapor in the air

Saturation occurs when

the air is holding as much water as it can, meaning it has reached capacity

—-air holds more water vapor than —- air

Warm air holds more water vapor than cold air

Saturation Vapor pressure

that part of the total pressure due to water vapor pressure in saturated air(mb)

Mixing rate

Weight of water vapor divided by Weight of dry air (g/kg)

Saturation Mixing Ratio

Weight of Water Vapor divided by the weight of saturated air

Relative Humidity

Mixing Ratio divided by Saturation Mixing Ratio; Actual water vapor divided by Capacity

If you( increase/decrease) temperature you (increase/decrease)relative humidity

If you increase the temperature, you decrease the relative humidity, and if you decrease the temperature, you increase the relative humidity

When is relative humidity the highest? Lowest?

Relative humidity is the highest at around sunrise and lowest from 3-5pm.

If you( increase/decrease) water vapor you (increase/decrease)relative humidity

If you increase water vapor, you increase relative humidity, and if you decrease water vapor you decrease relative humidity

North winds (increase/decrease) RH and South winds (increase/increase RH)

North winds decrease relative humidity while South winds Increase relative humidity

How does low pressure create clouds?

When air rises, it cools. Since there are fewer gas molecules on the surface, the air pressure is lower. As the air cools, humidity increases, ultimately forming clouds.

How does high pressure create sunny weather?

When air sinks, it gets warmer and the pressure increases. As the air warms up hu,midity decreases and sunny skies prevail

Larger differences between dew point and temperature mean..

Lower Relative Humidity; No difference means 100% Humidity

What is a sling psychrometer?

It calculates the dew point temperature and, ultimately, the relative humidity. If there is a high difference on this tool, it means low RH, and a low difference means high RH.

Dew Vs Frost

Dew: Forms on clear, calm nights where the temperature is > 32 degrees farenheight, condensation is the phase change that occurs

Frost: Forms on clear, calm nights where the temperature is <32 degrees farenehight, deposition is the phase change that occurs

Fog

Cloud Bases at or near earth’s surface

What fogs form from cooling?

-Advection fog- Warm, humid air moves across a cooler surface (thick dense fog)

-Radiation fog-Warm, humid air cools after sunset( common in valleys, FL- calm winds, patchy fog)

-Upslope fog-Warm, humid air moves up mountain

What fogs form from evaporation?

-Precipitation fog-Raindrops evaporate, then air cools after sunset as colder air moves in

-Steam fog-Always forms over water: Lake water evaporates, recondenses as cooler air moves over the lakeC

Clouds

-Massive accumulations of tiny water droplets or ice crystals

What are the preffixes for clouds and what do they mean?

-Cummulus-Puffy shaped

-Stratus-Layered (overcast-no shape)

-Cirrus-Wispy or feathery

-Cirro-High level clouds

-Alto- Middle level clouds

-Nimbus-Rain producing

What are high level clouds defined by? Name them (3)

-Bases >3.5 miles

-Composed of Ice Crystals

-Non-Precipitating

(Cirrus, Cirrocumulus, Cirrostratus)

What are middle level clouds defined by? Name them (2)

-Bases @ 1.5-3.5 Miles

-Composed of Ice crystals or water droplets

-Non-precipitating

(Altocumulus, Altostratus)

What are low level clouds defined by? Name them (3)

• Bases @ <1.5 miles

• Composed of water droplets

• Can produce precipitation

  • (Cumulus, Stratus, Stratocumulus, Nimbostratus)

What are the thunderstorm clouds called? How are they defined?

Cumulonimbus

-Bases in low levels

Top extends to high levels

Geostationary Satellite

22,300 mi

-Moves about the same speed as earth

-Monitors Storms

Polar-Orbiting Satellite

500 mi

-Moves around from pole to pole

-Photographs data sparse regions

-Twice daily-complete coverage

Infrared Vs Visible Satellite Images

-Infrared: available 24hrs, low-level, warm, non-precipitating appear as gray, high-level, cold, precipitating appear as white

-Visible: Only available during daylight hours, High resolution, Able to see individual clouds, All clouds appear white