2.6: Length of Day and Insolation vs. Latitude
- Page ID
- 39742
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Length of day
In the previous section, we learned that the angle of incoming sunlight received by a region varies with the season. Not only do the seasons affect the angle of incoming sunlight, but they also greatly influence the length of the day. You may have already noticed that during summer, our days are longer, while in the winter, our days are shorter. This is emphasized in Figure \(\PageIndex{1}\), which shows how the length of day varies monthly for several given latitudes.
Figure \(\PageIndex{1}\): Length of day versus month of the year for several latitudes. (CC-BY-NC 4.0; Alicia Mullens). Alternative description of image.
Examine the monthly variation in day length for each of the latitudes provided in Figure \(\PageIndex{1}\), as the number of hours of sunlight received is shown on the Y-axis, while the month of the year is shown on the X-axis. The latitudinal variation in the length of day is reflected in the curve's amplitude (how high/low the line goes).
- The Equator experiences ________ variation in day length from season to season while locations at latitude 70°N experience _________ variation in day length from season to season.
- significant; almost no
- some; significant
- almost no; significant
- How does the month-to-month variation in day length change with latitude?
- The variation becomes smaller at higher latitudes
- The variation becomes larger at higher latitudes
- There is no variation with latitude
Total Insolation
Seasonal changes in The Angle of Insolation along with The Length of Daylight ultimately result in seasonal variations in Insolation received at a latitude, as shown in Figure \(\PageIndex{2}\). This is what ultimately affects how temperatures change with seasons.
- As you travel north from the Equator, the seasonal variation in Insolation:
- becomes larger
- becomes smaller
- does not change
- While all other latitudes have one peak in Insolation in June, the Equator has two peaks, which occur in:
- June and December
- March and September
- March and December
- June and September
- What is interesting, is that during June, the North Pole (90°N) receives ________ sunlight than the equator.
- more
- less
We know that with higher latitudes, the angle of insolation becomes lower, so based on what was covered earlier in this investigation, we can conclude that the biggest cause for these latitudes receiving more sunlight than the equator is the length of the day; granted, the sun may be low on the horizon during polar summer, but if the sun is out all 24 hours of the day, that grants a major opportunity for tremendous amounts of warming. As such, polar regions experience tremendous temperature differences from winter to summer, whereas tropical regions may experience a small, if noticeable, change.