Altitude and latitude are two primary factors known to affect the temperature variations on Earth's surface because varying altitude and latitude create unequal heating of Earth’s atmosphere. Latitude refers to the distance of a location on Earth's surface from the equator in relation to the North and South poles (e.g., Florida has a lower latitude than Maine); while altitude is defined as how high a location is above sea level (think: a city in the mountains has a high altitude).
Variation in Altitude
For every 100-meter rise in altitude, the temperature decreases by about 1 degree Celsius. High-altitude regions, such as mountainous places, experience low temperatures. Earth’s surface absorbs heat energy from the sun. When the surface warms up, the heat diffuses into and warms the atmosphere, and in turn, transfers some of the heat to the upper layers of the atmosphere.
Therefore, the layers of atmosphere closest to Earth's surface (low-altitude areas) are typically warmer compared to layers of atmosphere in higher-altitude areas.
Although higher altitudes typically experience lower temperatures, this is not always the case. In some layers of the atmosphere (such as the troposphere), the temperature decreases with increasing altitude (note: this is referred to as "lapse rate").
Lapse rate occurs during cold, winter nights when the sky is clear and the air is dry. On nights like these, the heat from Earth's surface radiates and cools faster than atmospheric air. The warmer surface heat then also warms the low-lying (low-altitude) atmospheric air which then rises rapidly into the upper atmosphere (think: because warm air rises and cool air sinks).
Consequently, places located in high altitudes, such as mountainous regions, experience high temperatures. Usually, the average lapse rate in the troposphere is 2-degrees Celsius per 1,000 feet.
Angle of Incidence
Angle of incidence refers to the angle at which the sun's rays strike Earth's surface. The angle of incidence on Earth's surface depends on the region’s latitude (distance from the equator). In lower latitudes, when the sun is positioned directly above Earth's surface at 90 degrees (like it looks at noon), the radiation from the sun strikes the Earth’s surface at right angles. In response to the direct radiation from the sun, these regions experience high temperatures.
However, when the sun is, say, at 45 degrees (half of a right angle, or like mid-morning) above the horizon, the sun’s rays strike Earth's surface and spread out over a larger surface area with less intensity, making these regions experience lower temperatures. Such regions are located further from the equator (or at higher latitudes); therefore, the further you go from the equator, the cooler it becomes. Regions closer to Earth’s equator experience higher temperatures than regions near the North and South poles.
Diurnal variation is the change in the temperature from day to night and often depends on latitude and Earth’s rotation on its axis. Normally, Earth receives heat during the day via solar radiation and loses heat through terrestrial radiation at night.
During the day the sun’s radiation heats Earth's surface, but the intensity depends on the length of the day. Some days are shorter than others (think: seasons). Regions with longer days (typically regions near the equator) will experience more intense heat.
During winter at the North and South poles, the sun is below the horizon for 24 hours. These regions experience no solar radiation and remain constantly cold. In the summer at the poles, there is constant solar radiation, but it is still typically cold (warmer than winter at the poles, but colder than summer near the equator).
So, the intensity of solar radiation on Earth's surface depends on latitude, the sun’s altitude, and the time of the year (aka--a combination of altitude and climate). Solar radiation intensity can range from no radiation during polar winter to maximum radiation of about 400 watts per square meters during summer.