L. 2: Climate as it relates to water; C.1-Oki Flashcards
Saturation Vapor Pressure
Vapor pressure at saturation point according to clausius-clapeyron equation (max amt of water air can hold at a given temperature)
Vapor pressure
Amount of water in air, partial pressure exerted by water vapor molecules
Relative humidity
Ratio of actual vapor pressure to saturation vapor pressure. Temperature controls the saturation vapor pressure.
Warm air holds more water vapor (higher temperature = less condensation)
Higher saturation pressure = more water molecules in vapor form at the point of saturation.
Clausius-clapeyron relationship
= amount of water that a parcel of air can hold as vapor is a function of temperature.
Evaporation
Draws latent heat from Earth’s surface. This is the energy required for phase change of water from liquid to gas. It thus cools the surface adding in the distribution of solar heating to the atmosphere.
That heat is stored in the water molecules as they are carried away by the atmosphere, ready to be released once clouds form / condensation occurs.
E - P
Indicator of water availability. When negative, area has lots of water, equator, where more energy from sun at direct angle and higher temperature, and at high latitudes.
E-P is positive, dry, positive energy in subtropics (~30 N/S), less energy as approach poles, but have water, so negative ET.
Buoyancy
Tendency of object to float in a liquid, controlled by differences in density between that object and the fluid.
Density of air parcels controlled by temperature. If parcel of air is warmer than the surrounding air because heated it up near the ground, that parcel will be less dense, more buoyant, and will ascend.
Precipitation
Global patterns controlled by general circulation of atmosphere.
Need air that contains water vapor (humidity) and need to move this air up in the atmosphere where it can cool, so water vapor can condense and form clouds and rain out.
Varies by latitude, and spatially and from season to season.
Circulation
Surface heating at equator, energy surplus, causes uplift in atmosphere, allowing subtropical air to flow into the surface low pressure (counter-clockwise rotation), creating convergence, intertropical convergence zone.
This air flows sideways to the subtropics where it cools and sinks and warms, which suppresses precipitation, diverging at the surface (high pressure clockwise rotation). Flows back to equator and creates trade winds (Hadley cell).
Mid-latitudes 30-60 degrees (Ferrel cell) (NYC 45 degrees).
Equatorial low; subtropical high; subpolar low; polar high.
Heat Capacity
The amount of energy required to raise the temperature of a system. The heat capacity of water and oceans is about 4x as large as the heat capacity of land, so 4x as much energy is needed to raise the temperature of a given volume/mass of ocean vs. land. Thus, oceans (and other waters) have a moderating effect on climate: warmer than land in winter and cooler than land in summer.
During day, land heats up more than adjacent sea, so breeze from high pressure ocean to low pressure land. At night, land cools more rapidly, so breeze from high pressure land to low pressure sea.
Mediterranean Climate
Wet winter, dry summer (when within Hadley cell)
Monsoon Climate
Wet summer, dry winter, caused by differential heating of the land/ocean.
Deserts
Dry all year round because: (1) permanent high pressure in mid-latitudes; (2) center of continents far from moisture source; (3) rain shadows (orographic precipitation); or (4) coastal regions with cold ocean currents.
Tropical rainforests
Warm, wet all year round. Often some seasonality due to migration of ITCZ.
Climate Change
Warmer atmosphere can hold more water, will increase ET. For precipitation, some areas get dryer, some wetter, but intensification of average pattern. Wetter high latitudes, drier subtropics. Precipitation changes more uncertain (especially in Indian monsoon and Amazon basin regions) because more processes involved (humidity, energy, etc.)
