Temperature Controls

Why Temperatures Vary Throughout the Country

San Francisco vs Washington DCS.F. and D.C. are almost at the same latitude but do they have the same weather?43 deg in S.F., while it’s -10 deg in D.C.

So What’s Going On?Land vs Water: land heats more rapidly &

to higher temps than water.Land also cools more rapidly and to a much

lower temp than water.San Francisco has a big ocean just up wind

from it.Washington D.C. has a big continental land

mass just up wind from it.

Factors that vary temps.San Francisco and Washington DC are both at the same latitude, same altitude. Their geographic position is different combined with Land vs Water.

LatitudeLand vs waterAltitudeGeographic positionCloud coverOcean currents

AltitudeTemperature falls with an increase in

altitudeLapse rate - 3.6 deg F every 1000’ in

altitude or 6.5 deg C every 1000 m. Thus snow on the mt. and not in the valley

Rain Shadow Due to Lapse Rate

Cloud Cover & Albedo• Albedo tells you how

much radiation is reflected back into space by any surface.

• Clouds have a high albedo and can cool the land.

• At night clouds do the opposite and keep heat in – always warmer after a cloudy night.

Isotherms• The prefix Iso means

“same”• Therms mean

temps., thus isotherm = same temperatures

• On a weather map, isotherms are lines of equal temperature – remember “topo maps”?

Lab Set-Up

Can we test the assumption that land heats faster and cools faster than water?

That’s our lab.